eGuide to Storage

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					           eGuide to Storage
The definitive guide to all things Network-attached Storage
                       February 2009
eGuide to Storage                                                                                                          SearchStorageAsia

                                                               Table of Contents

      eGuide to Storage........................................................................................................................... 1
      EDITOR’s COLUMN ....................................................................................................................... 3
      Pop Quiz: NAS................................................................................................................................ 3
      Back-to-Basics: Network Attached Storage .................................................................................... 4
      Moving from DAS to NAS ............................................................................................................... 5
      Managing Petabytes of Data? It’s a Breeze .................................................................................... 6
      Dispelling myths about clustering NAS and file servers .................................................................. 8
      Clustered NAS gaining in popularity ............................................................................................... 8
      Understanding NAS interconnects: Fast Ethernet and Gigabit Ethernet ....................................... 10
      Planning for NAS .......................................................................................................................... 11
      One more time: NAS FAQs........................................................................................................... 11
      How to create an RFP for NAS ..................................................................................................... 13
      NAS appliance purchase considerations....................................................................................... 13
      NAS management software purchase considerations................................................................... 14
      NAS gateway purchase considerations......................................................................................... 16
      Answers to Pop Quiz on NAS ....................................................................................................... 17

      Contact the editor
      Victor Ng, editor –
      Jose Allan Tan, content director –

      Advertise. To find out more about our solutions contact:
      China, Hong Kong SAR
      Michelle Palmer, Associate Publisher
      Tel: +852 2589 1326
      Fax: +852 2559 7002

      Southeast Asia
      May Yee Tan
      7500A Beach Road, #11-313/315 The Plaza, Singapore 199591
      Tel: +65 6395 4581
      Fax: +65 6297 7928

                                                             Page 2 of 17
  eGuide to Storage                                                                 SearchStorageAsia

Nothing without money! That is what you get when you need help. As an old friend used to remind me:
nothing’s free in this world! Well, we hoped to change the rules here at SearchStorageAsia. This is our 10th
free eGuide and our topic for this issue is Network-attached Storage or NAS.

eGuides are a great tool for keeping tabs of what’s happening in the storage arena. We make it simple by
compiling the best stories and tips around specific topics. Of course they have to be around storage.


              Jose Allan Tan
              Content Director

Pop Quiz: NAS
By SearchStorage editors

Network-attached storage (NAS) has been around for many years now. NetApp or Network Appliance as it
was formerly called literally started the industry. So before we even start you on your way to knowing all there
is about NAS, a pop quiz should set you on the path to discovering whether you really knkow enough about
NAS to make a profession out of it.

Are you a NAS nerd or a NAS neophyte? Take our test and evaluate your knowledge of NAS protocols, NAS
interconnects and more. All of the answers can be found at the end of this eGuide.

1. The newest interconnect for NAS devices is               7. The goal of this is to boil your vendor choices
high-bandwidth and low-latency.                             down to a manageable few, then pit those
Your answer: _________________________                      vendors in a battle based on features you outline
                                                            as important.
2. The emergence of this technology came about              Your answer: Hint: Three words
as a result of poor NAS management.                                  _________________________
Your answer: Hint: Two words
         _________________________                          8. This type of system offers far more Ethernet
                                                            ports than traditional NAS systems.
3. This is the best-documented NAS interconnect             Your answer: Hint: Three words
for connecting.                                                       _________________________
Your answer: Hint: Two words
          _________________________                         9. Although is has been used for years in SANs
                                                            as a cheaper alternative to Fibre Channel, this
4. This connection offers a way for you to attach           protocol is new to NAS, and provides block-level
your NAS to your SAN.                                       access to storage.
Your answer: Hint: Two words                                Your answer: _________________________
                                                            10. This is prominent in clustered NAS systems
5. You'll want to use this type of protocol in a            because all nodes in the cluster can concurrently
Windows-heavy environment or when cross-                    share the same pool of storage, allowing nodes to
platform compatibility is paramount.                        act independently or together.
Your answer: Hint: Four words                               Your answer: Hint: Three words
          _________________________                                   _________________________

6. This type of storage combines multiple arrays            Score card
or controllers to increase performance, capacity or
reliability.                                                10 correct: You're a NAS nerd
Your answer: _________________________                      7-9 correct: You're NAS notable
                                                            4-6 correct: You've got NAS, but no nerve
                                                            0-3 correct: You're still a NAS neophyte

                                             Page 3 of 17
Back-to-Basics: Network Attached
By Stephen J. Bigelow, Features Writer

Network-attached storage is a class of dedicated hard disk-based file storage devices. Rather than storing
data on disks allocated on file servers scattered throughout an organization, a NAS device provides central,
consolidated disk storage available to LAN users through a standard network connection.

Most NAS systems receive an IP address, connect to the LAN through an Ethernet cable, and reside on the
LAN as an independent network device. NAS devices can also be part of a SAN. Although IP is the most
common network protocol, many NAS products support other network protocols, such as Novell Inc.'s IPX
and Microsoft's NetBEUI. NAS products can share and exchange files using established file sharing protocols
such as Sun Microsystems Inc.'s NFS or Microsoft's CIFS open standard. Other protocols allow NAS "boxes"
to operate across a wider variety of network infrastructures.

NAS devices offer storage administrators the abilities to expand and consolidate their storage infrastructures.
Network storage no longer relies on disks in a local server. And since storage is no longer limited by the
number of disks that a server can hold, a NAS product can hold numerous disks (and can easily include
enough disks to support RAID), and multiple NAS "boxes" can be attached to the network for extensive
storage expansion. In most cases, a single NAS box can replace numerous file servers, resulting in significant
consolidation. If one NAS box runs short on storage, more NAS boxes can easily be installed.

For instance, the FAS270 from Network Appliance Inc. offers up to 16TB of raw capacity using up to 56 disk
drives in a 3U 19-inch rack mount. With user storage taken out of the local server, network users don't
demand the server's processing time for mundane storage tasks, which in turn improves performance of local
application servers. NAS systems also include some onboard RAM to cache network data to or from the
disks. Small NAS devices may only provide a 128 MB to 256 MB cache; enterprise-class NAS systems may
offer cache of 8 GB or more.

Although some NAS boxes will run a standard operating system like Windows, many NAS devices run their
own proprietary operating system. For example, the NAS platforms from NetApp use the company's
proprietary Data ONTAP operating system. NAS platforms are typically managed and configured using
integrated software utilities that run across any standard Web browser. This allows storage administrators to
check NAS status, diagnose performance issues and make changes to the NAS configuration from any
workstation on the LAN. Management utilities are able to manage heterogeneous multiple NAS boxes as
more storage is added to the infrastructure, easing the management burden on storage administrators.

NAS systems are denoted by their drive support, the total number of drives and total capacity/expandability.
SCSI drives are one common drive type and SAS drive compatibility is available, but by far the most popular
drive type supported at this time is SATA, which offers low-cost bulk storage. Workgroup-type NAS systems
generally support 1 TB and up of disk storage. Basic NAS units employ a group of four to six hard disks,
though some models support expansion disk racks that allow extended storage up to 30 TB. Enterprise-class
NAS systems can implement many disks, to achieve capacities well over 100 TB.

The network interface can become a LAN bottleneck for storage traffic. Since a NAS can replace many
individual file servers, the storage traffic that had previously been distributed throughout the data center or
organization is now centralized in one system. In other words, the connectivity must scale to service the
concentration of storage. Many NAS products support Gigabit Ethernet (GigE) for faster data transfers across
the network. Some NAS products provide dual (or even quad) GigE connections for improved network
performance and interface redundancy (e.g., failover or port aggregation).

As NAS technology extends further into the enterprise, the need for performance also grows -- establishing
the notion of "high-performance NAS." Substantial NAS deployments need more throughput to pass ever-
growing volumes of data between disks and the network. This means better internal disk controllers for more
IOPs and additional connectivity to support higher network traffic. Most high-performance NAS platforms
employ global file systems for extensive data access, and the systems are often tuned to optimize data
streams for specific applications such as transactional data handling or media file streaming. NAS systems
can sometimes achieve better performance by clustering NAS nodes together, but clustering alone is no
guarantee of added performance.
 eGuide to Storage                                                                SearchStorageAsia

Moving from DAS to NAS
By Rick Cook                                              The ideal files for NAS are reasonably sized,
                                                          commonly used by multiple users (especially in
Although storage area network (SAN) and                   the same department or office) and do not have
network-attached storage (NAS) technologies are           very high-performance requirements. While some
gaining in popularity, direct-attached storage            companies have moved transaction processing
(DAS) is still the most common kind of storage,           applications onto NAS appliances, that usually
especially in small-midsized businesses (SMBs).           isn't considered ideal because of the potential for
In fact, SMBs typically start their networks with         network congestion.
storage attached to their network server and
sometimes they never need anything more.                  It is important to note that thin provisioning (TP)
However, as the volume of data and the number             on NAS works fine if your network isn't too heavily
of users grows, DAS becomes harder to manage.             loaded. However, if you've got an active TP
That is when companies start looking at the next          application, your network is likely to be the first
step in storage. While some of those companies            bottleneck.
go directly to a SAN, the most common next step
is to add storage to the existing network in the          Before installing a NAS system, spend some time
form of NAS.                                              understanding your users' requirements.
                                                          Determine the files and applications that are most
When to move                                              often shared, as well as which DAS systems are
                                                          running low on storage. Also look for duplicate
The reason to move from DAS to NAS is                     DAS files and folders that can be eliminated by
economics. NAS is the easiest and least                   putting a single copy on NAS. Such duplication is
expensive way to add storage to a network, so             a common response to the performance problems
most SMBs that are moving away from DAS start             of using a file on someone else's computer over
with NAS. This is often done in the form of               the network. The remote user copies the file over
inexpensive NAS filers, which combine disk                to get more speed.
storage and network connectivity in a single box,
along with enough smarts to manage everything.            Getting a file from a NAS box over the network is
                                                          not going to be as fast as getting it from DAS on a
In general, the more network-centric your                 user's computer. But it should be considerably
operation, the more you need to consider NAS or           faster than getting it from another user's computer
a SAN. Likewise, as users start to bump against           and perhaps faster than getting it off the server.
the capacity of their DAS, they should consider
whether to add storage to a bunch of systems or           Bandwidth
add a single, more efficiently utilized chunk of
storage to the network. NAS, even with simple             The most common problem with adding NAS filers
NAS appliances, costs more per gigabyte than              is the extra load they put on the network. Because
adding a new disk drive. But the higher utilization       the files will be traveling back and forth over your
and ease of allocation can easily cover the added         network, NAS has the potential to cause network
cost.                                                     congestion, especially if your network is already
                                                          heavily loaded.
One of the biggest advantages of low-end NAS is
simplicity. Most NAS vendors, like NetApp, offer          This is less of a problem now that NAS appliances
inexpensive NAS appliances that can be brought            routinely come with built-in Gigabit Ethernet
up on a network in less than an hour by staff with        connections, but you may have to upgrade your
minimal training.                                         network to support NAS and keep adequate
                                                          performance. Remember that all the applications
NAS appliances range in capacity from a couple            on the network are likely to be affected by the
of hundred gigabytes to several terabytes of              added NAS load.
storage and in price from approximately $1,000 to
$50,000 or even more. Besides higher capacity,            Ideally, you want your NAS filer to be in close
the more expensive units feature more                     topological proximity to the servers and
sophisticated management and data backup                  workstations that are using those files. The more
tools.                                                    hops through gateways you have to make to get
                                                          from the filer to the destination, the more
Architecting NAS                                          performance will suffer.

The physical architecture of basic NAS is very            NAS and storage management
simple. The logical architecture -- what to move to
NAS and what to keep in DAS -- requires a little          Because NAS filers are so easy to add, there's a
more thought.                                             tendency to go overboard with them. That is,
                                                          companies keep adding them as departments

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 eGuide to Storage                                                                 SearchStorageAsia

need more storage without a lot of thought to the
overall storage architecture.                              Migrating data

Surprises aside, the big problem is trying to              The final step in moving from DAS to NAS is
manage a sprawling collection of NAS filers that           migrating everything to its new home. Moving the
have popped up over the network. NAS filers                data itself is straightforward. You can copy the
typically come with storage management                     files directly or restore them from a backup onto
software, but products with low-end NAS filers             the NAS appliance. The more difficult part of the
tend to be pretty basic and may not integrate well         job is making sure everyone can find their files in
with your company's own storage management                 their new locations.
                                                           In Windows, the basic method is to substitute the
Fortunately storage management software has                name of the new platform for the old server in the
become more NAS-aware and it is easier to                  Group Policy logon scripts. However, this won't
manage NAS filers on modern networks.                      work if a user is accessing the file through
However, it is important that your company has             something like dragging a shortcut of a folder onto
policies in place to manage the proliferation of           their desktop. In this case, DNS renaming might
NAS filers.                                                be the appropriate approach.

At some point it makes sense to go to more                 About the author: Rick Cook specializes in writing
sophisticated, more manageable NAS systems,                about issues related to storage and storage
such as NAS gateways, or to go to a SAN for                management.
most of your storage needs.

Managing Petabytes of Data? It’s a
By Tony Leung

Managing terabytes of data is now passé. For the first time, IT professionals are concerned about the
petabytes of data in their care.

According to analyst firm IDC, data storage will grow at more than 50 percent per year between 2008 to 2010.
IDC’s research also shows that 2008 is the year when disks sold for file-based data (such as media or office
files) will overtake the ones sold for block data (such as databases or email).

This data growth is driven by the growing use of rich media, such as streaming video embedded in computer-
training programs, webinars stored on corporate websites, and customer-facing web applications that are
storage intensive.

Another trend that will place tremendous demands on storage is the move towards Web 2.0 from both service
providers and from enterprise companies. As the Internet becomes a platform for mass collaboration and
computing, the rich applications available will demand an ever-growing amount of storage.

Take for example Snapfish, an online photo-hosting service HP acquired three years ago. Today, it hosts
about 5 billion images and has a total of 55 million customers. Adding about 1 million customers a month, this
translates into storage capacity of about 6 petabytes today that will see a phenomenal growth to about 20
petabytes by end-2010.

Even enterprise customers are experiencing this aggressive growth in storage requirements. This is driven by
the demand for digital archiving and the growing use of granular data.

Many companies are converting their analog archives that are typically paper documents into digital archives.
While tape is the traditional storage medium for archival data, some companies are opting for disk storage in
order to quickly and easily access and leverage this data where possible.

Applications have increased the granularity of the data used. For instance, digital cameras took photos in one
or two megapixels five years ago. Today, it is not uncommon for consumer digital cameras to support 10
megapixels photos. Digital television formats mean 13.5GB of storage space is needed for one hour of
encoded video, while even corporate databases are making use of new technologies like virtualization and
data cubes which demand substantial storage requirements.

                                           Page 6 of 17
 eGuide to Storage                                                                   SearchStorageAsia

According to Mark Peters, an analyst at Enterprise Strategy Group, many companies are struggling with file-
based growth – not only how to cope with the sheer growth, but also how to leverage their digital and static
media to create additional revenue by delivering online services.

Massive Storage Build-outs
Now with massive storage build-outs a necessity, an easy-to-manage and highly-scalable storage
environment is a must.

Today, a new generation of high-performance NAS systems promises to overcome past limitations, bringing
SAN-type features and capabilities to file-based storage. These new technologies are making such systems
available even to companies with limited IT budgets.

IT Managers have always liked the manageability of NAS solutions compared to alternatives like DAS (direct
attached storage) and SAN (storage attached network). However, NAS systems tend to fall short in terms of
its ability to scale capacity simply and economically. As a result the NAS market is split into two segments:
low-priced, low-performance, non-scalable devices that are suited for home offices; and more expensive
enterprise class devices that offer high-performance and scalability, but require specialized management

This is where scalable NAS comes in, to bridge these two extremes, and offer easy scalability and
manageability at an affordable price.

Scalable NAS would suit companies that anticipate dramatic data growth like those involved in any form of
rich media, such as video pre- and post-production, pre-press, 3D modeling, satellite imagery, and high-
performance computing.

Scalable NAS would also suit companies who need to deliver streaming video to users; provide Web 2.0 file
servers; digital archiving; storage massive amounts of data, whether as large individual files or as a large
number of smaller files.

Manageability, Scalability and Affordability
Compared to traditional NAS, scalable NAS offers several advantages. In terms of interfaces, high-
performance NAS will typically offer more Ethernet ports. A typical NAS box will have one or two Ethernet
ports, whereas scalable NAS can support anything from 10, 16 or more Gigabit Ethernet (GigE) ports.

Another advantage of scalable NAS over traditional NAS is the ability to easily scale both capacity and
throughput. These systems are able to pack a lot of computing power and storage capacity into each cubic
foot of data centre space they occupy.

Scalable NAS is also more manageable, requiring few administrators per petabyte of storage. This is
essential in an environment of massive storage, as new content and devices need to be added easily, and
both capacity and throughput need to scale easily. Adding additional storage modules or server blades should
be a simple, automated affair without significant downtime.

This would mean wizards or policy-based decision making, as well as having a single, unified interface that
streamlines all aspects of provisioning and configuration, allowing servers and storage to scale both together
and separately. Beware of scalable NAS systems that require special host software or drivers, or need
proprietary hardware and storage. Find a solution that allows interoperability with different storage systems, to
ease compatibility.

Industry Leading Integrated System
An early mover in the scalable NAS arena is HP, the No. 1 disk storage systems vendor worldwide by
revenues, according to analyst firm IDC’s report “IDC Worldwide Quarterly Disk Storage Systems Tracker
Q4’07,” March 2008.

The HP StorageWorks 9100 Extreme Data Storage System (ExDS9100) offers vast storage capacity and
simplified, integrated management out-of-the box.

With this system, HP has managed to get the cost of storage capacity down to start at less than $2 per GB,
making it suitable for the capacity and cost structure required by the IT shops of today.

The systems arrive from the vendor preconfigured, pretested with built-in management features that allow
rapid turnkey deployment of both the initial installation and any necessary upgrades.

Starting with a base of 246 terabytes, the ExDS9100 is based on HP’s c-Class BladeSystem, with the base
system comprising four processor blades. The system can be expanded incrementally to 820TB in the form of

                                           Page 7 of 17
  eGuide to Storage                                                                  SearchStorageAsia

blocks, each containing 82 terabytes and combined individually with an additional controller, drive and other
items to scale bandwidth and capacity.

One key attraction for HP's ExDS9100 is that it will only require a small number of IT staff. The system is also
entirely an internally constructed solution by a single vendor, consisting of HP hardware leveraging bladed
components, new management features and PolyServe clustered file software from to facilitate massive

Ultimately, companies need to grapple with this phenomenal growth of data storage. The highly competitive
nature of today’s business environment means that corporate data needs to be on-demand and immediately
accessible. Given the tight IT budgets in companies, the scalable NAS system is certainly a highly viable
system for sites that anticipate a high degree of data growth.

About the author
Tony Leung is Product Marketing Manager for Scalable NAS and PolyServe at the HP’s StorageWorks
Division in Asia Pacific and Japan.

Dispelling myths about clustering NAS
and file servers
By George Schultz

What you will learn: Many myths have sprouted                Myth: Clustered storage is only for large IT
up about clustered storage because the term is               environments.
used to describe so many different kinds of                  Reality: Clustered storage can simplify things for
vendor offerings. Here we'll dispel some of these            small sites leveraging modular growth in terms of
myths.                                                       performance or capacity or ease of management.

Myth: Clusters are not grids, grids are not                  Myth: Clustered storage is only for
clusters.                                                    performance applications.
Reality: The grid police may not agree, but a                Reality: Clustered storage is effective for NAS
cluster is a grid and a grid is a cluster. A cluster         consolidation, as well as home directors, and bulk
can be local or remote and can use proprietary or            storage, including near-line archiving of structured
open solutions just like a storage grid. Some                and unstructured data.
vendors will try to mask a cluster by calling it a
grid in an attempt to make it sound unique.                  Myth: More ports, processors, nodes,
                                                             networks and devices guarantee more
Myth: Clustered storage is only for HPC.                     performance.
Reality: Some vendors only support high-                     Reality: It's not just about the number of
performance computing (HPC) parallel or                      components or speeds and feeds. More nodes,
sequential data access. Others support                       ports, memory and disks do not guarantee more
concurrent and random small I/Os, including                  performance for applications.; It depends on how
metadata lookup from any node in the cluster.                those resources are deployed and how the
                                                             storage management software enables those
Myth: Clustered storage is only for parallel or              resources to avoid bottlenecks. For some
sequential access.                                           clustered NAS and storage systems, more nodes
Reality: Some solutions also support OLTP, as                are required to compensate for overhead or
well as general file serving, while others can               performance congestion owhen f processing
handle bulk storage applications cost-effectively.           diverse application workload and performance

Clustered NAS gaining in popularity
By George Schultz

Using clustering technology to scale the performance, capacity, connectivity and availability of servers isn't
new. Clustered storage, however, is another matter.

                                            Page 8 of 17
 eGuide to Storage                                                                   SearchStorageAsia

While clustered storage is often associated with high performance computing, the reality is that mainstream
commercial environments are adopting clustered storage at a rapid rate. These businesses are attracted by
the way clustered storage now leverages established technologies such as Ethernet, Fibre Channel and
InfiniBand protocols, by its reliance on open access methods such as NFS and Windows CIFS, and by its use
of industry-standard servers and third-party storage.

The clustered storage solutions enjoying the highest growth rates may be network attached storage (NAS) file
servers. Deployments of this technology are being driven by the need of organizations to scale beyond the
limits of a single storage box to handle structured and unstructured data.

Clustered NAS systems offer scaling advantages on many levels:

    •    scaling in performance of large sequential bandwidth (throughput) or small random IOPS
         (transactional) and meta data lookup;
    •    scaling in storage capacity;
    •    scaling availability on a local or distributed basis to isolate against device or site failure;
    •    scaling of flexibility, including concurrent access of the same or different data along with parallel
         access of data for different application needs;
    •    scaling in terms of offering modular (pay-as-you-grow) storage growth; and
    •    scaling in ease of manageability of tasks such as provisioning of storage, load balancing and data

Approaches to NAS and file serving clustering

The technologies that most companies are clustering are storage, file systems and file servers. Clustering
adds standby or failover capabilities to storage systems that in turn support scaling with a large number of
controllers, storage nodes or processors along with clustered file systems. One reason for the confusion in
discussions of clustered storage is that there are block-based (iSCSI and Fibre Channel) and file-based (NAS
NFS and CIFS) storage, virtual tape libraries and other types of clustered storage solutions.

Clustered file systems enable administrators to access a common pool of storage across application servers.
Clustered file systems also permit shared access (read and write) of data files, which is useful for maintaining
data consistency and integrity whether using direct-attached or networked storage. Examples of clustered file
systems are SGI CXFS, Quantum StorNext, Red Hat GFS and IBM SFS and GPFS. Not all clustered NAS
boxes have a clustered file system and not all clustered file systems rely on clustered NAS servers. Some
systems (for example, IBRIX Fusion) combine both.

What differentiates a clustered fileserver from a traditional NAS file server or clustered storage system is the
way hardware and software is combined. A clustered file system can be installed on application servers or on
dedicated appliances or servers, transforming them into storage servers (essentially, becoming a clustered
fileserver). Some clustered fileservers, such as HP PolyServe or IBRIX Fusion, are hybrids that enable a
clustered and/or parallel file system deployed on industry-standard servers.

Some vendors who have dual or redundant storage controllers, storage engines, NAS heads or gateways
using active/active (both controllers working) or active/passive (one controller in standby) modes claim to offer
clustered storage systems. All I can say is that if you consider a pair of storage processors or controllers as a
cluster, you'd have to consider every storage system with at least two nodes a cluster. . .which would
encompass pretty much all of the mid-range SAN, DAS and NAS storage systems in the marketplace.

There are many more vendors providing clustered NAS storage (in other words, beyond basic failover) and,
more importantly, clustered fileservers. NAS, by its nature, is a file serving solution that sits on top of
hardware and in some cases has the ability to transform the hardware into a clustered fileserver. Examples of
NAS hardware/software solutions that also support clustering of file systems and the underlying hardware
include NetApp GX, BlueArc Titan, and offerings from Isilon and Panasas.

Isilon and Panasas use proprietary processors and storage. BlueArc uses optimized processors that attach to
and share access to underlying RAID-equipped storage from several vendors. Other examples leverage
clustered file system software installed on industry standard servers transforming them into storage servers
such HP PolyServe and IBRIX Fusion among others.

About the author: Greg Schulz is founder and senior analyst with the IT infrastructure analyst and consulting
firm StorageIO Group. He is also the author of the definitive book on storage networking, Resilient Storage
Networks, published by Elsevier, and is a regular contributor to Storage magazine and other TechTarget

                                           Page 9 of 17
 eGuide to Storage                                                                    SearchStorageAsia

Understanding NAS interconnects: Fast
Ethernet and Gigabit Ethernet
By Tory Skyers

Storage managers use NAS interconnects are used to integrate NAS devices into their networks.
Understanding NAS interconnects can help storage administrators make better decisions about how to deploy
their NAS systems.

The best-documented NAS interconnect for connecting is Fast Ethernet, (FastE, 100 Mbps). While FastE is
low-priced and easy to understand, it is slow for all but the most basic file-level chores. FastE is adequate for
workgroups of 10 or fewer people transferring documents under 10MB in size. Once you get to larger
documents, you'll reach the limits of FastE and will want to upgrade to the next level of interconnect: Gigabit
Ethernet (1000 Mbps).

GigE is suited for a wider range of NAS interconnect tasks. With GigE, you can service a surprisingly large
group of people transferring 10.1 MB files and larger. Even 100 people accessing the server at FastE speeds
will see reasonable performance.

However, GigE will start feeling sluggish when you're servicing groups of 500 people, transferring a large mix
of large and small files. You'll also see only workable performance when you start using protocols that offer
block-level access to your NAS devices.

For these situations, our friends in the Ethernet networking world have come up with 10 GigE (10,000 Mbps).
The newest member of the Ethernet family, 10 GigE is by far the fastest and can offer serious performance
for even the most demanding of file environments. Most makers of enterprise NAS devices offer a choice of
mix-and-match Ethernet connections. Price is usually the governing factor in choosing your interconnects.
Generally speaking, the more expensive the device, the more exotic the interconnects are.

Fibre Channel connections are normally reserved for SAN devices, but NAS vendors have started including
Fibre Channel as well. Fibre Channel interconnects are offered in speeds of 2 Gbps, 4 Gbps and 8 Gbps.
Fibre Channel encompasses both a protocol and an interconnect. As most enterprise SAN solutions cannot
offer file sharing, NAS vendors offer ways for you to attach your NAS to your SAN using Fibre Channel. This
allows you to open the storage you have in your SAN to file-level access through your SAN.

NAS devices also use Fibre Channel to offer low-latency, high-bandwidth block-level connections to multiple
hosts. Fibre Channel has a leg up on GigE when it comes to bandwidth and latency, but competes on an
arguably even performance playing field with 10 GigE. For those who want to leverage their investment in
Fibre Channel, this interconnect offers the most value. A word of caution: Not all NAS vendors support Fibre
Channel, and should you have it installed in your environment, you'll want to make compatibility a part of your

The newest interconnect for NAS devices is InfiniBand, a super-high-bandwidth, super-low-latency
interconnect often used for high-performance computing clusters. InfiniBand started at around 10 Gbps and
rumor has it 40 Gbps will be coming to market soon. (Just typing 40 Gbps brings a smile to this network
administrator's face.)

With InfiniBand, we are talking about some extremely high bandwidth, with the ability to transmit a full-length,
DVD-quality movie in three seconds. These interconnects are currently offered by only a handful of NAS
vendors and are relegated to demanding environments, one of which I wish were my basement lab!
InfiniBand has had a slow start as an interconnect. But as virtualization, at both the host level and storage
level, gains steam in large-scale, non-mainframe systems, you'll see demand for such high-performance
interconnects become more mainstream.

About the author: Tory Skyers is a senior systems engineer for Prudential Fox & Roach Realtors, an
independently owned and operated member of The Prudential Real Estate Affiliates Inc. He frequently speaks
at conferences such as Storage Decisions and also contributes regularly to's blog called
Storage Soup.

                                            Page 10 of 17
 eGuide to Storage                                                                   SearchStorageAsia

Planning for NAS
By Tory Skyer

Planning for any form of centralized storage can be a daunting task, either you are in a position where you
have to deploy it immediately and end up with a tangled mess of files, folders and connections, or you are in a
protracted four-year planning cycle where every potential issue has an associated taxonomy diagram.

Following are some NAS planning basics, starting with location. Make sure you've identified and visited in
person where you are going to physically house the device, make sure the location has adequate power,
cooling and network access and be sure you have the physical room to install an uninterruptible power supply
(UPS) along with your NAS device. Often times some branch office NAS devices will end up in the
maintenance closet, along with high humidity, dust, poor power supply and a network cable that doubles as a
mop hanger. While not high on most engineers list of to-dos, the lack of power, cooling and access can turn
even the best-planned implementation into an expensive nightmare.

Power is one of the most basic needs of a NAS system. If you are not locating your NAS device in a
colocation facility or data center, be sure you pay careful attention to the power requirements for your device
when configured with its maximum load of disk -- this is key. Your system will grow, and if you plan ahead for
supporting the maximum electrical capacity of your chosen device, you will save yourself the potential for
downtime and costly construction. Planning for a UPS that can support your NAS for 10 minutes longer than it
takes for it to shutdown is also a good idea. It's important that you plan for brownouts and surges, and
upgrade your UPS when you add shelves to your NAS system.

Be sure you have adequate network bandwidth for your proposed usage. Flip back to the tip on interconnects
for a good rule of thumb when sizing network bandwidth. If you have a hub-and-spoke style WAN layout,
consider using compression and WAN acceleration devices that will reduce the impact file traffic will have
when coming from your branch offices back to your central location. Depending on the device you've
purchased, you may need more than one port and IP address. Some NAS devices aggregate multiple
network connections to offer higher performance, so plan contiguous ports on your network switch for this
type of expansion to reduce complexity and to ensure an easy bandwidth upgrade path.

Planning for storage allocation at the onset may cause planning paralysis. Do not, under any but the most
extreme circumstances, preallocate all of your disks the instant your NAS arrives, especially if it is your first
implementation of centralized storage. You will be tempted to carve it up and give all the business units or
departments their share right up front and then forget about it, but this will lead to under-allocation. Under-
allocation with no free disks mean your users will get a dreaded "out of disk space" error. While you will have
the technical ability to expand the volume you've created, you will have no disk to expand it to. So if marketing
has a big ad blitz going on, you are going to be their least favorite person. Over-allocation is a little more
difficult to deal with because while expanding volumes is technically possible, most common file systems will
not let you shrink them. So, if you've given 100 GB to accounting and it only uses 4 GB , you will have to copy
that 4 GB off the volume, destroy the volume, recreate a smaller volume and then copy the data back and
reattach it to the server.

Thin provisioning, which I covered in the RFP tip, will help with this problem.

One more time: NAS FAQs
By Ashish Nadkarni
                                                             Is NAS a better storage option for SMBs than a
What are the benefits of NAS for SMBs?                       SAN or a mixed solution?

The key benefit is the ability to consolidate                Absolutely, it is a much better option. NAS can
structured and unstructured data into a file-                leverage your existing IP infrastructure and very
sharing environment that utilizes the existing IP            rarely requires any additional hardware or
infrastructure. Since NAS clients rarely require             software for access. It easily integrates with
any additional hardware to access data, the initial          corporate security and authentication domains
investment is contained to the NAS array itself.             such as Radius, Active Directory and LDAP,
                                                             making it a very attractive option for SMBs.
What you find is that most NAS environments are
self contained and do not require any additional
software for basic functionality.

                                            Page 11 of 17
  eGuide to Storage                                                                  SearchStorageAsia

With NAS prices declining, which vendors are                 of consolidating various SAN islands into a single
positioning their offerings to fit the SMB                   solution. In a typical SMB environment, there is a
market?                                                      potential to have data strewn all over the place in
                                                             the form of ad hoc file-serving environments. User
What you'll find is that most major vendors such             data can stay resident on employee desktop and
as EMC, NetApp, Hitachi Data Systems and even                laptops, exposing it to the risk of getting lost or
HP have recognized the importance of having                  exposing it to unauthorized individuals.
some sort of NAS offering in the SMB space.
Most now offer lower cost or tiered solutions for            So by consolidating it in the form of virtualization,
these markets.                                               it allows your company to get rid of such SAN
                                                             islands and ad hoc file-serving environments and,
Additionally, several startups have come up that             more importantly, enforce a common policy for
offer NAS solutions for the SMB markets with                 security, data protection and access.
different options around lower cost disks.
Additionally, networked storage vendors such as              NAS virtualization is one of the ways you can
Netgear and Cisco now offer NAS solutions for                bring about this consolation. The other option to
the SMB space as well.                                       consolidating NAS is to invest in a scalable
                                                             environment and then migrate everything to this
Are there any best practices for selecting a                 new environment.
NAS system in an SMB environment?
                                                             Virtualization has been around for awhile. It hasn't
Cost is the primary driver for the SMB space.                gained or lost any popularity per se. Most vendors
Other things to consider are to determine if the             are now offering virtualization as a function in their
product is viable in the market, the serviceability          products, so it's something that you don't have to
and the ease of use, including the implementation            buy extra to install it.
and configuration.
                                                             Can you provide any tips for consolidating
Another thing to look for would be the                       NAS boxes?
environmental footprint, such as power and heat,
and even the rackability of that product. Other key          Some of the things to look at would be to examine
factors to examine would be backup and                       your data types and to consolidate it based on the
recovery, the ability to internally tier storage and,        different types of data stored on your file-sharing
of course, scalability.                                      environments. The other thing to look at would be
                                                             how this data is accessed and what are some of
What is clustered NAS and what are its                       the data access profiles.
                                                             For example, is this accessed on a daily basis,
Clustered NAS is typically defined as a concurrent           accessed once in a while or accessed in an ad
multi-node access to and servicing of data. This is          hoc manner? So classifying data in a loose sense
usually accomplished by implementing some kind               would allow you to consolidate it based on its
of distributed or clustered file system that allows          profile.
any node to serve data regardless of where it's
located or who actually owns it.                             The other thing to do is to take a stock of how this
                                                             data is accessed. Is it accessed on a single
In a traditional NAS environment, the filer head             network in a corporate office or is it accessed by
actually owns that data and that is typically what           remote connections? If they're remote
serves it -- very much like a server-based file-             connections, look at how having a file-sharing
serving environment. If the server or head goes              environment in a single home office can benefit
down, you can typically have a passive or a                  remote offices.
standby node pick it up and serve that same
storage.                                                     Lastly, look at how much you are willing to invest
                                                             in a single NAS solution that is a one-size-fits-all
Traditionally, NAS has suffered from a scalability           approach. It might just turn out that consolidation
issue at the higher end and the inability to service         is an expensive option if you're going to invest all
multiple concurrent connections. Clustered NAS               of it in one shot.
overcomes these limitations by dynamically
distributing client connections to multiple heads.           You may look at a tiered solution or a pay-as-you-
The key thing with clustered NAS is again cost,              go solution, which will allow you to start small, and
which will need to be considered in the SMB                  as you start migrating stuff to the new
space.                                                       environment you can grow. That way you're not
                                                             making a huge initial investment and you have a
Do you believe virtual NAS solutions can fit in              chance to try it before you invest.
an SMB environment?
                                                             Ashish Nadkarni is the Principal Consultant with
Virtual NAS solutions do fit into an SMB NAS                 GlassHouse Technologies Inc.
environment, as long as you can find the benefit

                                             Page 12 of 17
How to create an RFP for NAS
By Tory Skyer

Some may wonder why a request for proposal, or RFP as it's usually called, is important when it comes to
NAS devices. The answer is that while an RFP isn't the same as a project plan, it can certainly help you
define your success criteria in selecting a NAS system.

The goal of an RFP is to boil your vendor choices down to a manageable few, then, based on the criteria in
your RFP, pit those vendors in a battle to the death, based on features you've outlined as important. There
are no hard and fast rules for an effective RFP, but there are a few generic steps you can take to create a
solid RFP and get the NAS device best suited for your environment.

Before starting an RFP, you should have a good idea of what you need. Most vendors will have installed most
of their devices in different environments and have a good idea of where their products fit well and where they
don't. While such information is valuable in the selection process, it limits you to only one vendor's point of
view. By distributing an RFP to multiple vendors, you will get a broader range of situations to consider.

Start your RFP by putting together, in layman's terms, a list of the things you want your device to do. For
example, a NAS device will need to connect to multiple VMware servers with no performance loss, or a NAS
device should only consume the disk space that files use and nothing more. While you'll have to do a little
homework into the technologies currently offered in the NAS space, you don't need to be an expert to put
together a list of things you want to buy.

Putting your technical wish-list in simple terms makes it easier for you to match up the techno-speak with real-
world execution and for your accounting department to understand when it comes budget time. Your RFP
doesn't have to be long and complex. Short and simple will probably yield much better results -- two to three
paragraphs and some bullet points should suffice for all but the most complex NAS deployments.

Next, think about what you need. If your budget allows it, hire a consultant for four to eight hours to help you
get a handle on some of the current technologies. The consultant should be vendor-neutral, perhaps from a
VAR like CDW, SoftChoice or More Direct. (Some VARs even offer this service for free.) With the expert's
help, you should be able to put together a solid shopping list of available technologies and put the RFP out to

I've made a point here of not suggesting particular technologies, but one specific technology is worthy of any
and all RFPs: thin provisioning. Thin provisioning allows you to avoid the over- and under-provisioning issues
outlined in the planning tip. You will only consume the disk space you have actually used to store files.

About the author: Tory Skyers is a senior systems engineer for Prudential Fox & Roach Realtors, an
independently owned and operated member of The Prudential Real Estate Affiliates Inc. He frequently speaks
at conferences such as Storage Decisions and also contributes regularly to's blog called
Storage Soup.

NAS appliance purchase considerations
By Stephen J. Bigelow, Features Writer

Network attached storage (NAS) appliances are frequently touted for bringing convenience and simplicity to
network storage. Appliances include their own dedicated disks for storage and RAID, and most NAS
appliances can be upgraded with more or larger disks for additional storage space. If even more storage is
required, another NAS appliance can be added to the network. NAS devices typically run their own
proprietary operating system (OS) and are managed and configured using integrated software utilities that run
across any standard Web browser. This allows storage administrators to check NAS status, diagnose issues
and make changes to the NAS configuration from any workstation on the local area network (LAN).

However, NAS appliances do pose some disadvantages. First, they are file-based and not appropriate for
every application -- some applications simply need the SAN . Second, their LAN connectivity can present a
potential bottleneck for network users trying to access storage. Consequently, the choice of NAS appliance
requires careful evaluation. Now that you've reviewed the essential issues involved in any NAS product, this
guide focuses on specific considerations for dedicated NAS appliance products. You'll also find a series of
 eGuide to Storage                                                                  SearchStorageAsia

specifications to help make on-the-spot product comparisons between vendors, like Agami Systems, Dell Inc.,
EMC Corp., IBM, ONStor Inc., Sun Microsystems Inc. and more.

Watch for additional or hidden fees. Not all of the features listed for a NAS appliance are standard. Some
features and functionality may carry additional costs for upgrades or software licensing, adversely impacting
the TCO. When comparing product costs, be sure to compare costs with all necessary features enabled, and
factor in any upgrade or licensing costs involved in future scalability.

Consider the capacity and connectivity. Select a NAS appliance that will offer adequate storage capacity in
the near term and suitable expandability into the future. An undersized NAS appliance will typically force
users to purchase additional appliances -- resulting in additional capital expense and management overhead.
Also, ensure that the NAS appliance provides suitable Fibre Channel (FC) or Ethernet connectivity with
enough ports to support the expected storage traffic. For example, the Snap Server 18000 from Adaptec Inc.
incorporates two Gigabit Ethernet (GigE) ports for connectivity. By comparison, IBM's N7000 Modular Disk
Storage System supports up to 12 GigE ports or up to 16 2 Gbit FC ports.

Consider any necessary infrastructure changes. Heavy data transfers can easily overwhelm a LAN.
Understand the implications of traffic changes on the intended network segment, and plan to accommodate
upgrades or infrastructure changes that might be needed to achieve best performance. For example, adding
a standalone NAS to a lightly used network segment may require a move from 100 Mbps Ethernet to GigE or
the utilization of multiple GigE ports in busier environments. Organizations that need the performance of SAN
storage may opt for a NAS gateway, rather than a NAS appliance. The NAS vendor might be able to help with
network planning.

Consider the platform implications. The choice of platform can have a profound impact on the scalability,
performance and manageability of NAS devices. Industry experts note that appliances based on Microsoft
Windows (e.g., Windows Storage Server 2003 Release 2) are typically simpler to implement and manage,
while proprietary appliances, such as EMC Corp.'s Celerra or Network Appliance Inc.'s (NetApp) products,
often support greater scalability and performance. Proprietary appliances sometimes integrate more
functionality, such as snapshots, which can add significant value to an enterprise.

Evaluate the support for RAID. Most NAS appliances offer data protection through internal RAID, so consider
the RAID levels that will be most beneficial for your appliance. Support for RAID 0 (striping), RAID 1
(mirroring) and RAID 5 (parity) is common. RAID 6 (double parity) is appearing in appliances that rely on
high-density SATA disk -- though support for RAID 6 is not yet universal. For example, Adaptec Inc.'s Snap
Server 18000 and EMC's Celerra support RAID 1 and RAID 5, but the StoreVault S500 includes RAID-DP; a
variation of RAID 6 double parity. Remember that your choice of RAID will impact the total usable storage
capacity of the appliance. For example, RAID 1 mirrors disk contents, effectively cutting the total storage
capacity in half. RAID 5 requires a disk in every RAID group dedicated to parity data. RAID 6 demands two
additional disks in every RAID group for parity data.

Consider other forms of NAS data protection. Beyond local RAID features, a NAS appliance may offer
support for snapshots, replication and backup. Be sure to identify the suitable snapshot or replication targets;
a NAS appliance that can replicate to any heterogeneous storage platform may be preferable to an appliance
that can only replicate to a duplicate heterogeneous appliance. Industry experts emphasize the importance of
backup and recovery compatibility -- the NAS appliance should be compatible with your existing
backup/recovery software and should not impose any special requirements on backup or recovery processes.
As an example, the Adaptec Snap Server 18000 integrates BakBone Software Inc.'s NetVault software and
offers backup agent support for Veritas, CA Inc., NetWorker and NDMP tools.

Consider internal support for tiered storage. Some NAS appliances can provide internal support for multiple
disk types, and this can be a notable feature for organizations that practice tiered storage; for example, the
Pantera 2200 Clustered NAS from ONStor supports serial attached SCSI (SAS) disks for performance and
SATA disks for high-volume storage. This allows NAS appliances to be included within storage tiers. In many
cases, both drive types can be supported simultaneously for internal tiering.

NAS management software purchase
By Stephen J. Bigelow, Features Writer

                                           Page 14 of 17
 eGuide to Storage                                                                  SearchStorageAsia

Network attached storage (NAS) management software allows administrators to deploy, configure, allocate
and maintain NAS appliances and gateways within the data center -- and often across the entire enterprise.
Typical NAS management software might automatically discover a vendor's storage resources in a network,
manage and adjust RAID configurations, back up NAS contents to standard backup software, track storage
utilization and offer capacity growth predictions, and even monitor other storage systems that it cannot
directly control.

While NAS management software is increasingly versatile, it is also more complex, so the selection process
requires careful consideration. This Buying Guide focuses on NAS product issues and provides a series of
specifications to help you make on-the-spot comparisons between products from vendors such as Attune
Systems Inc., EMC Corp., Hitachi Data Systems Inc., IBM and Microsoft Corp.

Evaluate the software's suite of features. Because NAS management software offerings vary dramatically, it's
important to determine the features you'll need initially as well as anticipate those that may be useful down
the road. Features include snapshots, local and remote mirroring, NDMP support, virtual servers, clustered
and enterprise namespace support, transparent data movement and migration, transparent failover,
performance and activity monitoring and alerts, WORM drive compatibility, support for large file systems and
lots of small files, NFS and CIFS support, along with file virtualization (e.g., aggregation, data movement and
replication). Features and capabilities vary with the software platform. For example, Windows Storage Server
2003 may be easy to configure, but a more proprietary platform, such as IBM's System Storage N series
software, may offer superior performance or scalability.

Consider the system requirements. NAS management software is typically installed on a server, so this
demands an available server that meets the software's requirements for operating system, CPU, memory and
other computing resources. This is usually no problem for larger businesses, but it may be a problem for
smaller organizations with limited server availability -- especially if the available server is already running
other software.

As an example, Adaptec Inc.'s Snap Server Manager software requires a Pentium III 133 MHz processor, 128
MB RAM, Snap Server GuardianOS v2.6 or higher, Snap Server SnapOS v3.4 or higher and Java Virtual
Machine V1.4.1. Server virtualization can further strain resources, since the physical server is carved up into
multiple logical servers that all draw simultaneously upon the same CPU and other computing resources.
(See the product specifications page for other details.)

Evaluate the tool's hardware interoperability. Since it's cumbersome and impractical to use a different
management tool for each NAS device, companies should select software that can support numerous NAS
devices across the organization. This means committing to NAS products from a single vendor or selecting a
tool that can support NAS devices from different manufacturers. Recognize the scope of NAS appliances or
gateways supported by the software and determine whether the management tool can cover the entire
organization adequately.

Evaluate the tool's management interoperability. Many NAS management tools can function through network
management tools already in use in the organization, such as Hewlett-Packard Co.'s OpenView, SNMP, SMI-
S, Java, HTTP, HTTPS or XML. This lets administrators run NAS management tools through their existing
management platform, instead of having to learn and operate the NAS management software as a separate
tool and process. While that may not pose a problem for limited NAS deployments where NAS management
overhead is limited, but can become an bottleneck in environments where NAS overhead is heavy.

Evaluate the role of NAS virtualization. NAS management may also include virtualization capabilities that
allow multiple NAS platforms to appear as a single storage resource. This makes it easier for administrators
to allocate storage and improves overall storage utilization because no NAS systems are left "orphaned" and
forgotten in the enterprise. One solution is to implement a distributed file system, creating a global
namespace between servers and NAS boxes. In other cases, virtualization is implemented through hardware
appliances that pool individual NAS filers. As the number of NAS boxes grows, the efficiencies offered by
virtualization should be considered more strongly.

Consider the level of automation available. Management software becomes more valuable when it can
automate many of the most common storage management functions, including resource
location/identification, provisioning, software updates and routine maintenance functions. NAS management
software should schedule important tasks like software updates or backups during off-peak hours.
Management tools should provide notifications and alerts in response to critical storage conditions, such as
low availability of storage. Some NAS management tools also handle capacity growth, which helps
administrators track storage utilization and plan upgrades. Staying ahead of needs is a key issue in
preventing application downtime and maintaining storage performance.

                                           Page 15 of 17
 eGuide to Storage                                                                  SearchStorageAsia

Consider the cost impact. Beyond the up-front cost of acquiring software, remember that some features and
functionality may be optional, and including them will add to the cost. Many software tools also require yearly
license (aka software maintenance) fees that will multiply the tool's cost over time. Weigh the software's value
against its TCO, which should include all necessary onetime and recurring fees.

Consider the management skill set. Effective storage management requires working familiarity with the tools
in use. New management tools, or tools from different vendors, demand training and practice for proficiency.
Administrators and other key IT staff need to be adequately trained. In some cases, training is included as
part of the acquisition cost. If not, the costs should be included in the product's TCO.

NAS gateway purchase considerations
By Stephen J. Bigelow, Features Writer

Network attached storage (NAS) appliances typically contain their own internal storage resources. Storage
capacity is expanded by simply adding more disks to the appliance. Obviously, this only allows users to scale
up to the capacity limit of the appliance. NAS gateways overcome these inherent limitations of scale and
flexibility by utilizing externally connected storage. In some cases, the external storage may be a standalone
disk array. It's also common for a NAS gateway to share storage through a storage area network (SAN),
allowing users to consolidate their NAS data on SAN storage and realize the benefits of high performance
and redundancy. Major NAS vendors offer tools that can migrate data from NAS appliances to their NAS
gateway products, which can also support all NAS protocols and many operating systems environments. Now
that you've reviewed the essential issues involved in any NAS product, this Buying Guide focuses on specific
considerations for NAS gateway products. You'll also find a series of specifications to help make on-the-spot
product comparisons between vendors, like EMC Corp., Hewlett-Packard Corp. (HP), IBM, Network
Appliance Inc. (NetApp) and more.

Evaluate interoperability between the gateway and storage. Not all gateways work with every storage
subsystem. This is particularly important if you're connecting to SAN storage. For example, the Bobcat Series
NAS gateway from ONStor Inc. supports disk arrays from disk array vendors, including Hitachi Data Systems
Inc. (HDS), EMC, IBM and HP. It's important to start by checking the vendor's compatibility matrix, but in-
house testing is also strongly encouraged to verify compatibility.

Even NAS gateways have capacity limits. Even though a NAS gateway is intended to use external storage
resources, there is still a finite limit that the gateway can address. For example, Hitachi NAS Blades can be
clustered to support up to 512 terabytes (TB) per cluster. This isn't a problem for most organizations today,
but potential storage limits should always be considered when planning a new gateway deployment.

Remember that some features move to the storage. By moving storage outside of the NAS gateway,
remember that some features will be dependent on the storage subsystem(s) being used. For example, an
NS700 series NAS gateway from EMC does not provide RAID or disk scrubbing, but the gateway supports
Symmetrix and Clariion storage, which does include RAID and disk-scrubbing features. Changing storage
platforms may add new features or remove existing features, and this can easily change the way that data is
managed through the gateway. Storage administrators must consider how changes to the storage
infrastructure will influence NAS capabilities.

Consider the connectivity. With external storage, connectivity is essential to ensure adequate performance
across the user base. In most cases, you can expect an array of Ethernet and Fibre Channel (FC) ports. As
an example, the StorageTek 5320 NAS gateway from Sun Microsystems Inc. provides four standard
10/100/1000 Base-T Ethernet ports and two dual-port 2 Gbps FC HBAs, with up to two optional dual-port
10/100/1000 Base-T ports. The IBM N5000 gateway is similar with four full-duplex 10/100/1000 Base-T
Ethernet ports and four 2 Gbps FC ports onboard. Connectivity not only supports expansion, but connections
can also be used to enable highly available features, such as failover for reliability or port aggregation for
improved performance.

Evaluate standard features. Pay close attention to the variety of features that ship standard with the NAS
gateway, including clustering, mirroring, replication, reporting, volume management and so on. For example,
the IBM N5000 gateway ships with a suite of software features, including FlexVol, snapshot, fast boot, email
alerts, NIS, DNS, SNMP, FilerView, NDMP, LDAP and AutoSupport. In addition, a gateway should support
the network protocols of any applications that will be using NAS storage, so consider the support for network
protocols, such as CIFS, FTP, HTTP and others.

                                           Page 16 of 17
 eGuide to Storage                                                                 SearchStorageAsia

Evaluate optional features and licenses. Don't just assume that every function and protocol is supported as a
standard feature. There are often many features available as options that can inflate both the initial and
ongoing costs of a NAS gateway. Examples of optional software features might include mirroring, restoration,
cloning and management tools. Even network protocols, like NFS, CIFS, HTTP and FCP, are considered
optional on the IBM N5000 gateway, along with their FlexClone, MultiStore, Clustered Failover (CFO),
SnapMirror, SnapRestore, SnapVault, SyncMirror, SnapValidator, SnapDrive for Windows, SnapDrive for
UNIX, Single Mailbox Recovery for Exchange, SnapManager for Exchange, SnapManager for SQL,
SnapManager for Oracle, Operations Manager, SnapLock Enterprise and LockVault Enterprise
software.Options and licenses can dramatically increase the gateway's TCO.

Consider the impact of virtualization. Virtual server capability allows NAS gateways to appear on the LAN as
a complete NAS device with a unique identity, IP address and security authentication. This allows NAS
gateways to be relocated, maintained and scaled without disruptions and data migrations. Storage
virtualization allows capacity to be added and configured as necessary, while eliminating wasted (unused)
storage space. Gateways, like the ONStor Bobcat, tout support for both types of virtualization.

Answers to Pop Quiz on NAS
    1.   INFINIBAND                                             6.    CLUSTERED
    2.   FILE VIRTUALIZATION                                    7.    REQUEST FOR PROPOSAL
    3.   FAST ETHERNET                                          8.    HIGH-PERFORMANCE NAS
    4.   FIBRE CHANNEL                                          9.    ISCSI
    5.   COMMON INTERNET FILE SYSTEM                            10.   GLOBAL FILE SYSTEM

Nothing to be ashamed of if you didn’t get them all! It took me several reads and a fair bit of reading on
searchstorageasia before I got to be a NAS Notable. You can do better. Come visit searchstorageasia for
everything you will ever need to know about NAS and other storage technologies.

*Editor's note:
For more learning guides, buyer's guides and Ask the Expert tips, visit the website at or sign up for your free weekly enewsletter.

2009 Copyright Questex Media All Rights Reserve

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