Learning Center
Plans & pricing Sign in
Sign Out

Choosing the Right Server


									     Choosing the
     Right Server

an        Networking eBook
[         Choosing the Right Server

                                                               Paul Rubens is an IT consultant based in Marlow,
                                                               England, and has been writing about business
                                                               technology for leading US and UK publications for
                                                               almost 20 years.


                                                                  2      The Evolution of the Server

                                                                  4      Working Out Your
                                                                         Server Requirments

 4                                    9                           9      The Availability Question

Choosing the Right Server, An Networking eBook.
© 2009, Jupitermedia Corp.

                        [           Choosing the Right Server                                        ]

                       The Evolution of the Server
                                              By Paul Rubens

                                                            But personal computers don't do all the work: they

  n the early days of corporate data processing, com-
  puters were large, expensive machines that were           need help. That's why in most organizations they are
  housed in their own dedicated computer rooms and          now connected to computers called servers, which as
operated by teams of white-coated technicians.              the name suggests, provide services such as sending
Programs and data were stored on special cards,             and receiving e-mail, and file storage. Servers are the
which were fed into the machine to be processed.            unsung heroes of the corporate computing environ-
Later on these machines could be operated from              ment, working behind the scenes to help get the max-
"dumb terminals": Teletype                                                          imum benefit from the per-
machines or keyboard-and-                                                           sonal computers that people
screen devices that allowed                                                         use every day.
users to share the processing
power of the mainframe com-                                                                     What is a Server?
                                                                                                The term "server" is a con-
                                                                                                fusing one, because it is used
The computing landscape
                                                                                                to mean two quite distinct
began to change radically in
the early 1980s with the intro-
                                                                                                • A software application that
duction of the personal com-
                                                                                                provides a specific set of
puter – the desktop device we
                                                                                                services to other computers
are familiar with today. With a
                                                                                                • A computer that provides
personal computer there was
                                                                                                services to other computers
no longer a need to share pro-                                                  Jupiterimages
cessing power: users could install and run whatever
                                                            For example, a server computer may run an e-mail
programs they needed on the machine on their desk.
                                                            server application and a Web server application. In
                                                            this case, the server (computer) could be said to be
Today, personal computers have become ubiquitous
                                                            running two servers (the e-mail and Web server appli-
in the workplace, but they no longer work in isolation.
                                                            cations). Just to confuse things further, a server com-
In a typical office scenario these computers are con-
                                                            puter running a single server application is often
nected to each by a local area network (LAN) that runs
                                                            known by the name of the application, so a server
throughout the building.
                                                            computer running an e-mail server application will be

          Servers are the unsung heroes of the corporate computing environment,
        working behind the scenes to help get the maximum benefit from the personal
                            computers that people use every day.

2                                                     ”
                                                    Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                          [           Choosing the Right Server                                         ]
called "the e-mail server."                                    the special requirements of a server mean this is usu-
                                                               ally not practical.
For the purposes of this eBook, the term "server" will         In general, a server needs to have the following attrib-
be used to refer to server hardware – the physical             utes:
computer that is acting as a server.                              • Speed. A server is expected to provide services to
                                                                  many client computers at once, and the purpose of
Why Are Servers Necessary?                                        having a server is defeated if doesn't have the
                                                                  power to provide these services quickly. To do this,
If you just have a single personal computer in your               servers are often equipped with microprocessors
organization, then you probably don't need a server.              that are more powerful than normal desktop com-
In fact, even if you have two or three computers work-            puter processors, and more random access memory
ing independently, you still may not need a server.               (RAM).
                                                                  • Large storage capacity. If a server is to act as a
But once you have two or more computers, it's com-                central storage repository, it needs plenty of disk
mon to connect them over a network. That's because                space to accommodate everyone's needs. While a
networking allows computer users to share files and               desktop computer will typically have just one disk
information easily. A document stored on one com-                 drive, it's not uncommon for a server to have four or
puter can be accessed and worked on from another,                 more.
and duplication of work can be avoided. A network                 • Reliability. When a server breaks down, many
also allows one computer user to print out documents              people in the organization may be unable to do
on a printer connected to different computer on the               their work, and the business as a whole may not be
network. A network, in other words, can increase the              able to function. Servers are usually built using high-
productivity of the people using it, and allow people             quality components that tend to be more expensive
to share resources such as a printer.                             than normal ones. They are also usually built to be
                                                                  fault tolerant – many are supplied with an extra
But there are downsides to this type of networking.               power supply that can take over if the primary one
Whenever one computer user accesses a document                    fails, for example – and have "hot swappable" parts
stored on another computer it causes that computer                that can be removed and replaced without having
to slow down. If many users are trying to retrieve or             to turn the server off. A technology called RAID is
store documents from the same computer they may                   also usually employed to ensure that data is not lost
find they have to wait an inconvenient amount of                  even if a hard drive fails completely. Server operat-
time. Anyone actually trying to carry out his or her              ing system software is also designed for maximum
own work on that computer is also likely to find it too           stability to minimize the chances of crashing, and to
slow to be practical. Far from increasing productivity            minimize the need for rebooting the system.
then, a network can slow everything down, actually                • Security. This can include a lockable case for
reducing productivity.                                            physical security, as well as a server operating sys-
                                                                  tem that has been hardened to minimize the
At a certain point, it makes sense to relieve the bur-            chances of intrusion by malicious hackers.
den of any individual user's machine by having a ded-
icated computer that is capable of providing file stor-        Additionally, it's usually desirable to have a long and
age and print services – or any other services that may        comprehensive warranty and service agreement.
be required – to all the users in the organization
quickly and reliably, so that productivity can go up,          Because of all of the above, it should be no surprise
not down. This is a server.                                    that servers generally cost more than desktop
                                                               machines, and it's usually wise to stay away from low-
Why is a Server Different from a                               cost servers from unknown vendors: the extra cost of
Personal Computer?                                             buying a good quality server from a well-known man-
                                                               ufacturer is likely to be insignificant compared to the
In a small business with just a few users, it is possible      cost to your organization if a server fails and prevents
to use a "spare" personal computer as a server, but            you from carrying out your business. I

3                                                      Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                          [           Choosing the Right Server                                        ]

          Working Out Your Server Requirments

                                                              Print Server
        here are a number of requirements you need to
        explore before purchasing your server. They
                                                              Significant savings can be made by allowing many
        include: server role, form factor, operating sys-
                                                              users to share a printer connected to a print server
tem, processor, and storage. Before buying a server,
                                                              instead of providing each user with his or her own
it's vital to decide exactly what you want your server
                                                              printer. Typically, the roles of file server and print serv-
to do – both now, and in the foreseeable future. Here
                                                              er are combined into a single file-and-print server.
are some typical roles that a server can fulfil:

File Server                                                                                        E-Mail Server
                                                                                                   In small organizations, e-mail
A file and print server pro-
                                                                                                   is typically received and for-
vides a place for users to
                                                                                                   ward by a third party – usu-
store files, which may or may
                                                                                                   ally an Internet service
not be shared with other
                                                                                                   provider (ISP). Medium and
users. One advantage of
                                                                                                   large organizations frequent-
using a file server rather than
                                                                                                   ly run their own e-mail sys-
storing files on individual
                                                                                                   tem – often Microsoft
users' PCs is that it is much
                                                                                                   Exchange, IBM Lotus
easier to back-up a single file
                                                                                                   Domino, or Open-Xchange –
server than it is to back up
                                                                                                   on a dedicated e-mail serv-
the files on many different
personal computers. Backing
up a server can easily be                                                          Jupiterimages

automated and scheduled for a convenient time (such                                                Other Roles
as the middle of the night) while backing up individual       • Web Server: making Web pages available over the
computers can be complicated if they have been                Internet
switched off or, in the case of laptops, disconnected         • Intranet Server: publishing information for internal
from the network and removed. The data on a single            use within an organization
file server is also much easier to protect against theft      • Database Server: holding corporate information
or intrusion than multiple machines throughout the            from one or more corporate applications
organization.                                                 • Application Server: running applications that are

     Before buying a server, it's vital to decide exactly what you want your server to do –
                          both now, and in the foreseeable future.

4                                                       ”
                                                      Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                          [           Choosing the Right Server                                        ]
Form Factor Chooser
                                   Tower                               Rack Mounted                          Blade
Single server required             Suitable                            Not suitable                          Not suitable

Total number of servers            About 10 max                        10+                                   40+
in organization

Limited floor space                Not suitable for more               Suitable                              Suitable
                                   than small number

accessed by users with special client software running        tain power supplies and efficient cooling systems to
on their personal computers, or simply via a Web              dissipate the heat that such a large concentration of
browser such as Internet Explorer.                            computing resources can produce.

Form Factor                                                   The advantage of the rack-mounted server form factor
                                                              is that large numbers of servers can be accommodat-
Form factor is the term given to the overall size and         ed in a small area of floor space. Rack mounting can
shape of the server, which is determined by the case          also significantly simply power and network cabling
or housing into which all the components are fitted.          requirements.
These include:
Tower                                                         Since the standard rack-mounted server form factor is
If you are only intending to buy a very small number          1U, this is, in theory, the smallest form factor a rack-
of servers, and are unlikely to need more, then a             mounted server can have. In practice there are even
tower form factor is probably the best choice. A serv-        smaller servers, called blades, which can be rack
er with a tower form factor is a self-contained unit that     mounted.
looks much like a standard desktop PC -- although it
is likely to be slightly taller, allowing it to accommo-      Blade servers are extremely thin, stripped down
date as many as 10 disk drives.                               servers, which are fitted into a blade enclosure. A
                                                              blade enclosure may have a 10U form factor but
In fact, there are a variety of tower form factors, which     could contain 16 blades. The blade enclosure itself
in descending order of height include: Full tower, mid        often contains components such as network adapters
tower, mini tower, micro tower.                               and power supplies that are shared by all the blades
                                                              in the enclosure, allowing the blades to be made as
Rack-Mounted Server                                           small as possible.
Bigger organizations that require larger numbers of
servers tend to choose a more compact and easy-to-
manage rack mountable form factor. The standard               Operating System
rack-mounted form factor is 19 inches wide, and 1.75          While desktop computers use an end-user operating
inches deep, which is known as one unit, or simply            system such as Microsoft Windows XP or Vista, or SUSE
1U. Servers and other equipment are made with a               Linux Enterprise Desktop, servers run operating sys-
depth or thickness of multiples of 1.75 inches, so a          tems that are tailored to the special needs of servers.
server may have a 1U, 2U, or even 6U form factor.
                                                              In general, a server operating system is designed for:
Rack-mounted servers are housed in a standard server          • Stability
rack that is 42U high. A server rack can therefore            • Reliability
house 42 1U servers, 21 2U servers, or combinations           • Security
of rack-mountable devices with a combined height              • Ability to offer services to multiple client machines
that does not exceed 42U. Server racks usually con-           simultaneously

5                                                     Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                           [           Choosing the Right Server                                        ]
Your choice of operating system may be largely deter-
mined by the use to which you intend to put the serv-             In general, the main considerations that determine
er. For example, if you intend to use the server as a             the choice of server operating system are:
mail server running Microsoft Exchange, you will need             • Skill sets of your staff. If no one in your organiza-
a Windows server operating system – either Windows                tion is familiar with Linux then it is not a practical
Server 2003 or Server 2008. Similarly, if you want to             choice
run the popular open-source Web server Apache, you                • Total cost of ownership. Linux software is freely
will need to run a Linux operating system such as                 available while Windows software involves both
SUSE Linux Enterprise Server or Ubuntu Server                     server and client access license fees. However,
Edition.                                                          license fees are only a component – together with
                                                                  support -- of the total cost of ownership of a server
For less specific applications, such as running your              operating system.
server as a file server, the choice of operating system           • Compatibility with any applications you wish the
is much wider. Even if the majority of desktop com-               server to run.
puters in your organization are running Windows
operating systems, the file servers can run:                   Processors
    • Windows Server                                           Linux and Windows-based servers usually run on
    • Any flavor of Linux server operating system,             processors made by either Intel or AMD. It is possible
    • Mac OS X Server operating system (this can only          to run a server using a standard Intel or AMD desktop
    run on Apple Macintosh hardware, and would nor-            processor, but in practice it is more common to use a
    mally only be run in an organization which uses            more powerful processor specifically designed for use
    Apple Macintosh desktop computers.)                        in a server.
    • In very large organizations it may be preferable to
    run Unix operating systems such as Sun                     Intel Xeon Server Processors
    Microsystems's Solaris or HP's HP-UX.                      Intel offers three lines of Xeon processors:
                                                                 • 3000 sequence Dual or Quad core

Operating System Chooser
                               Windows              Linux                       Mac OS X Server                 Other
Predominantly a                Suitable –           Suitable if staff           Not suitable                    Not suitable
Windows environment,           Windows Small        have Linux skills
small organization             Business Server
                               2003 or Windows
                               Small Business
                               Server 2008

Predominantly a                Suitable –           Suitable if IT staff        Not suitable                    Suitable if IT staff
Windows environment,           Windows Server       have Linux skills                                           have UNIX skills
medium or large sized          2003 or Windows
organization                   Server 2008

Predominantly                  Not suitable         Possibly suitable           Suitable
Mac OS X                                            if IT staff have
environment                                         Linux skills

Running a particular           Depends on           Depends on                  Depends on                      Depends on
server based                   application          application                 application                     application

6                                                      Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                         [             Choosing the Right Server                                      ]
Processor Chooser
                               Intel                          AMD                                     Other
Small business                 Xeon 3000 sequence             Opteron 1000 range
                               Dual or Quad core

Medium sized business /        Xeon 5000 sequence             Opteron 2000 range
standard business              Dual or Quad core

Large business /               Xeon 7000 sequence             Opteron 8000 range                      UltraSparc T1
high performance               Dual or Quad core
data or transaction
intensive applications

Mission-critical               Itanium 2 9000                                                         UltraSparc T1 / T2
high end computing             sequence

                                                               Redundant Array of
    • 5000 sequence Dual or Quad core

                                                               Inexpensive (or

    • 7000 sequence Dual or Quad core

In addition, it offers the very high-end Itanium 2 9000        Independent) Disks (RAID)
                                                                      ince one of the key attributes of a server
                                                                      discussed earlier is reliability, it follows
AMD Opteron Server Processors
                                                                      that the server's storage system must be
AMD offers thee lines of Opteron processors
                                                               reliable. For this reason it is very common for a
• 1000 range
                                                               server's hard disks to be configured using RAID
• 2000 range - up to two per server

                                                               technology to introduce redundancy. When
• 8000 range – up to eight per server

                                                               disks are configured in a RAID array, one or
                                                               more disks can fail and be replaced (often with-
Other Processors

                                                               out the need to shut the server or storage device
Linux, and Sun's Solaris Unix-based operating system

                                                               down) without any data being lost.
can also be run using Sun Microsystems's UltraSPARC

Storage                                                        RAID works by copying the contents of the
                                                               disks in an array to one or more others in the
All servers need a storage subsystem to hold the               array. When one disk fails and is replaced, the
operating system, applications, and data that they             contents of the failed disk can be rebuilt onto
need. This normally takes the form of one or more              the new disk from the content stored on the
                                                               other disks. The capacity of a RAID array is
hard disks, and these can physically be located inside
                                                               always less than the sum of the capacities of
the server case, or externally, connected to the server
                                                               the disks that make up the array.
by a cable or network connection.

                                                               There are a number of types, or levels, or RAID,
The most common type of hard drives are:

  • Serial ATA (SATA) drives

                                                               • RAID 1: mirrors the contents of one disk onto
  • Small Computer System Interface (SCSI) drives

                                                               another (and sometimes more than one other).
SATA drives tend to be cheaper than SCSI drives, but

7                                                    Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                         [           Choosing the Right Server                                        ]
SCSI drives are much faster, allowing a server to pro-
                                                               Redundant Array of Inexpensive (or
                                                               Independent) Disks (RAID)
vide services to clients much more efficiently in a busy

Hard drives are commonly available in capacities               No data is lost as long as at least one disk is
ranging from about 80GB up to 750GB or more.                   functioning. The capacity of the array is equal
Larger capacities are often achieved by increasing the         to the capacity of one disk; so two 500GB disks
areal density (i.e., the bits per square inch) of the          configured using RAID 1 result in an array with
disk's storage platters, and there is some evidence            a capacity of 500GB.
that disks with very high areal densities are less reli-       • RAID 5: the most common RAID level, RAID 5
able than those with lower densities when used in an           uses three or more disks in an array, and dis-
intensive server environment. Given this, is it wise to        tributes and copies the data across the disks in
specify a larger number of lower capacity disks (350 to        such a way that no data is lost if a single disk
500GB) than a few very high capacity disks (750GB+)            fails.
                                                               • RAID 6: this is similar to RAID 5, but can tol-
Internal Hard Drives                                           erate up to two disks failing without any data
The simplest storage option is to use hard drives fit-         being lost. I
ted inside the server. Servers may sometimes house
six or more hard drives, giving a storage capacity of
between 2 and 6 TB without RAID.
                                                                • Storage Area Network (SAN): a storage area net-
External Hard Drives                                            work is actually a complex system which connects
Many servers use storage disks that are physically              an array of disks (or other storage devices) to a serv-
located outside the server case. Devices that provide           er in a way that makes the storage look (to the serv-
external storage include:                                       er) as if it is attached directly. They tend to be
  • Direct Attached Storage (DAS): a device that                expensive and the preserve of large companies.
  contains one or more hard drives, connected to the
  server.                                                    When assessing your likely storage requirements con-
  • Network Attached Storage (NAS): a device con-            sider:
  taining one more hard drives, connected to the               • How much data you have now
  same LAN as the server. The server may have exclu-           • How much new data you are likely to create every
  sive use of the NAS, or the NAS may be used by               month
  one or more other servers or client computers.

Storage Chooser
                                   Internal disks              DAS                           NAS                          SAN
Single server                            Y                       Y                             Y

Multiple servers                                                                               Y                             Y

Storage requirement                      Y                       Y                             Y

Storage requirement                                      Y - multiple DAS           Y -multiple NAS
10TB to 100TB                                            devices required           devices required

Storage requirements                                                                Y – multiple NAS                         Y
 >100TB                                                                             devices required

8                                                    Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                         [            Choosing the Right Server                                        ]

                           The Availability Question

                                                                 memory modules, mirrored memory or hot-plug-

      ervers usually play an important role in a busi-
      ness, and if one or more is unavailable (i.e., is          gable RAID memory.
      not working) it can be anything from inconven-             • A server cluster: this involves two or more servers
ient to disastrous.                                              that are linked together and to a shared storage
                                                                 device. Usually one server, or cluster node, is put
Asking the following questions may help you get an               into operation, while the other waits as a standby
idea of the importance of                                        machine. If the standby machine sees that the other
server availability:                                                                         has failed, it takes over the
• How costly would it be for                                                                 duties that the failed
your business if a server                                                                    machine was previously per-
were unavailable for an hour,                                                                forming. Sometimes both
a day, or a week?                                                                            nodes in a cluster can work
• How much time can you                                                                      at the same time, but will
afford for a server to be                                                                    take over the duties of the
unavailable?                                                                                 other should it fail.
• How much time and                                                                          • A fault tolerant server:
money would it take to fix                                                                   fault-tolerant servers are
any problems caused by los-                                                                  designed from the ground
ing data if a server failed                                                                  up to work continuously,
unexpectedly?                                                                                even when components fail.
                                                                                             They do this by duplicating
Depending on your answers,                                                                   almost all of their compo-
it may be worth paying a                                                                     nents, so that any or all of
premium for a high-availabil-                                                                their vital parts can fail with-
ity server system.                                                             Jupiterimages out causing the server to
These include:                                                   stop operating. The components are "hot-swap-
   • A hardened standalone server: this is a server that         pable" so they can be replaced while the server is
   is fitted with extra parts such as an extra power sup-        running, and software monitoring alerts administra-
   ply and RAID storage, making it more reliable than            tors when components are beginning to fail so they
   a normal desktop machine. Companies such as HP                can be swapped out as quickly as possible.
   offer fault tolerant memory subsystems with spare

          A hardened standalone server: this is a server that is fitted with extra parts
         such as an extra power supply and RAID storage, making it more reliable than
                                  a normal desktop machine.

9                                                         ”
                                                      Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                         [          Choosing the Right Server                                       ]
Comparison Chart
                              Standalone server            Failover cluster                        Fault tolerant server
Cost                          Very low cost                Low to moderate cost                    Relatively high cost

Frequency of downtime         Quite frequent               Relatively frequent, but    Almost never
                                                           only for very short periods

Recovery time after           Hours or even days           Usually not more than                   Should never happen
a server failure                                           a few minutes                           except during a

Technical measures            Software needs               Some applications may                   Software needs no
                              no modification               need modifying to                      modification
                                                           become cluster aware.
                                                           IT staff need to manage

Space required                Single server                Two or more servers,                    Single server
                                                           could be in a rack

 Server Virtualization

       f you think you need more than one server, you may be able to cut your costs significantly
       through server virtualization – running two or more virtual servers on a single physical server

 Using virtualization software available from companies including Microsoft (its Hyper-V virtualiza-
 tion system is bundled with most versions of its new Windows Server 2008 operating system) and
 VMware, it is possible to use a single server to host multiple virtual servers running different operat-
 ing systems – a Linux virtual server running Apache Web server software, and a Microsoft Windows
 server running Microsoft Exchange, for example.

 The benefits of server virtualization are:
  • Lower hardware costs: virtualization obviates the need to purchase one or more physical servers
  • Lower maintenance costs: fewer severs means less components to go wrong
  • Lower power consumption: running a single physical server near to its full capacity is more ener-
  gy efficient than running multiple servers at lower capacity
  • Less floorspace required
  • Higher stability: running separate applications on their own virtual servers instead of on the
  same server reduces the likelihood that changes to one application can adversely impact another

 On the other hand, running many virtual servers on a single physical host server makes them all vul-
 nerable should the physical host break down. To counter this problem both Hyper-V and VMware
 offer a system suitable for larger organizations that can transfer the states of all the virtual servers
 to a backup physical host and resume their operations very rapidly.

 HP, Dell, and others will effectively be bundling Hyper-V when they supply servers running Microsoft
 Windows Server 2008 to their customers, and some vendors including HP and IBM are also offering
 the option of embedding VMware's ESX Server 3i virtualization product on their servers – on USB
 storage or a flash memory card that can be inserted to start the virtualized environment. I

10                                                 Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.
                       [           Choosing the Right Server                                       ]
Server Buyer’s Checklist
Server Role                                                          File and print server
                                                                     Mail Server
                                                                     Email server
                                                                     Web Intranet server
                                                                     Database server
                                                                     Application server
                                                                     Other server

Form Factor                                                          Tower
                                                                     Rack mounted

Operating System                                                     Windows Server 2003 or 2008
                                                                     Windows Small Business Server 2003 or 2008
                                                                     Linux Server
                                                                     Mac OS X Server
                                                                     UNIX / other

Processor                                                            Intel Xeon
                                                                     AMD Opteron
                                                                     SPARC / other

Storage                                                              SCSI or SATA disks+

High availability features                                           Redundant components
                                                                     Cluster system
                                                                     Fault tolerant system

Management software                                                  Many options available

Service / warranty                                                   1 year, 3 year, 5 year

Management Software
                                                                     1 hour response, same day, etc

As the number of servers in your organization grows, so too does the time and skills needed to manage them.
Keeping a single server running efficiently and ensuring that the latest operating system and application
patches have been applied is a very different matter to managing a large number of servers.

That's why many companies offer server management software to help automate and simplify the management
process. These products include HP's Insight Control and Microsoft's System Center family of management
products (and System Center Essentials software for smaller companies.)

Management software enables server administrators to monitor all servers from a single management console,
spot and fix potential problems, ensure servers are fully patched and virus-free, and reduce downtime and man-
agement costs.

11                                                Choosing the Right Server, An Networking eBook. © 2009, Jupitermedia Corp.

To top