Choosing the Right Server an Networking eBook contents] [ 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 2 The Evolution of the Server 4 Working Out Your Server Requirments 4 9 9 The Availability Question Choosing the Right Server, An Internet.com Networking eBook. © 2009, Jupitermedia Corp. 1 [ Choosing the Right Server ] The Evolution of the Server By Paul Rubens But personal computers don't do all the work: they I 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? puter. 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 things: 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 Internet.com 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 Internet.com Networking eBook. © 2009, Jupitermedia Corp. [ Choosing the Right Server ] Working Out Your Server Requirments Print Server T 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 er. 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 Internet.com 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: Blade 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 Internet.com 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 application 6 Choosing the Right Server, An Internet.com 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 applications 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 S • 7000 sequence Dual or Quad core In addition, it offers the very high-end Itanium 2 9000 Independent) Disks (RAID) sequence 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 processors. 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: including: • 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). continued SATA drives tend to be cheaper than SCSI drives, but 7 Choosing the Right Server, An Internet.com 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 environment. 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 <6TB 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 Internet.com Networking eBook. © 2009, Jupitermedia Corp. [ Choosing the Right Server ] The Availability Question memory modules, mirrored memory or hot-plug- S 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 Internet.com 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 catastrophe Technical measures Software needs Some applications may Software needs no no modification need modifying to modification become cluster aware. IT staff need to manage cluster Space required Single server Two or more servers, Single server could be in a rack Server Virtualization I 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 computer. 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 Internet.com Networking eBook. © 2009, Jupitermedia Corp. [ Choosing the Right Server ] Server Buyer’s Checklist Options Server Role File and print server Mail Server Email server Web Intranet server Database server Application server Other server Form Factor Tower Rack mounted Blade 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+ DAS NAS SAN 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 Internet.com Networking eBook. © 2009, Jupitermedia Corp.
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