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Choosing theRight Server


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contents

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

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

2 The Evolution of the Server

4 Working Out YourServer Requirments

9 The Availability Question4

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Choosing the Right Server

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In the early days of corporate data processing, com-puters were large, expensive machines that werehoused in their own dedicated computer rooms and

operated by teams of white-coated technicians.Programs and data were stored on special cards,which were fed into the machine to be processed.Later on these machines could be operated from"dumb terminals": Teletypemachines or keyboard-and-screen devices that allowedusers to share the processingpower of the mainframe com-puter.

The computing landscapebegan to change radically inthe early 1980s with the intro-duction of the personal com-puter – the desktop device weare familiar with today. With apersonal computer there wasno longer a need to share pro-cessing power: users could install and run whateverprograms they needed on the machine on their desk.

Today, personal computers have become ubiquitousin the workplace, but they no longer work in isolation.In a typical office scenario these computers are con-

nected to each by a local area network (LAN) that runsthroughout the building.

But personal computers don't do all the work: theyneed help. That's why in most organizations they arenow connected to computers called servers, which asthe name suggests, provide services such as sendingand receiving e-mail, and file storage. Servers are theunsung heroes of the corporate computing environ-ment, working behind the scenes to help get the max-

imum benefit from the per-sonal computers that peopleuse every day.

What is a Server?The term "server" is a con-fusing one, because it is usedto mean two quite distinct

things:• A software application thatprovides a specific set of services to other computers• A computer that providesservices to other computers

For example, a server computer may run an e-mailserver application and a Web server application. Inthis case, the server (computer) could be said to berunning two servers (the e-mail and Web server appli-cations). Just to confuse things further, a server com-puter running a single server application is oftenknown by the name of the application, so a servercomputer running an e-mail server application will be

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

Choosing the Right Server[ ]

The Evolution of the ServerBy Paul Rubens

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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.

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called "the e-mail server."

For the purposes of this eBook, the term "server" will

be used to refer to server hardware – the physicalcomputer that is acting as a server.

Why Are Servers Necessary?If you just have a single personal computer in yourorganization, then you probably don't need a server.In fact, even if you have two or three computers work-ing independently, you still may not need a server.

But once you have two or more computers, it's com-mon to connect them over a network. That's becausenetworking allows computer users to share files andinformation easily. A document stored on one com-puter can be accessed and worked on from another,and duplication of work can be avoided. A networkalso allows one computer user to print out documentson a printer connected to different computer on thenetwork. A network, in other words, can increase theproductivity of the people using it, and allow peopleto share resources such as a printer.

But there are downsides to this type of networking.Whenever one computer user accesses a documentstored on another computer it causes that computerto slow down. If many users are trying to retrieve orstore documents from the same computer they mayfind they have to wait an inconvenient amount of time. Anyone actually trying to carry out his or herown work on that computer is also likely to find it tooslow to be practical. Far from increasing productivitythen, a network can slow everything down, actuallyreducing productivity.

At a certain point, it makes sense to relieve the bur-den of any individual user's machine by having a ded-icated computer that is capable of providing file stor-

age and print services – or any other services that maybe required – to all the users in the organizationquickly and reliably, so that productivity can go up,not down. This is a server.

Why is a Server Different from aPersonal Computer?In a small business with just a few users, it is possibleto use a "spare" personal computer as a server, but

the special requirements of a server mean this is usu-ally not practical.In general, a server needs to have the following attrib-

utes:• Speed. A server is expected to provide services tomany client computers at once, and the purpose of having a server is defeated if doesn't have thepower to provide these services quickly. To do this,servers are often equipped with microprocessorsthat are more powerful than normal desktop com-puter processors, and more random access memory(RAM).• Large storage capacity. If a server is to act as acentral storage repository, it needs plenty of diskspace to accommodate everyone's needs. While a

desktop computer will typically have just one diskdrive, it's not uncommon for a server to have four ormore.• Reliability. When a server breaks down, manypeople in the organization may be unable to dotheir work, and the business as a whole may not beable to function. Servers are usually built using high-quality components that tend to be more expensivethan normal ones. They are also usually built to befault tolerant – many are supplied with an extrapower supply that can take over if the primary onefails, for example – and have "hot swappable" partsthat can be removed and replaced without havingto turn the server off. A technology called RAID isalso usually employed to ensure that data is not losteven if a hard drive fails completely. Server operat-ing system software is also designed for maximumstability to minimize the chances of crashing, and tominimize the need for rebooting the system.• Security. This can include a lockable case forphysical security, as well as a server operating sys-tem that has been hardened to minimize thechances of intrusion by malicious hackers.

Additionally, it's usually desirable to have a long andcomprehensive warranty and service agreement.

Because of all of the above, it should be no surprisethat servers generally cost more than desktopmachines, and it's usually wise to stay away from low-cost servers from unknown vendors: the extra cost of buying a good quality server from a well-known man-ufacturer is likely to be insignificant compared to thecost to your organization if a server fails and preventsyou from carrying out your business. I





There are a number of requirements you need toexplore before purchasing your server. Theyinclude: server role, form factor, operating sys-

tem, processor, and storage. Before buying a server,it's vital to decide exactly what you want your serverto do – both now, and in the foreseeable future. Hereare some typical roles that a server can fulfil:

File ServerA file and print server pro-vides a place for users tostore files, which may or maynot be shared with otherusers. One advantage of using a file server rather than

storing files on individualusers' PCs is that it is mucheasier to back-up a single fileserver than it is to back upthe files on many differentpersonal computers. Backingup a server can easily beautomated and scheduled for a convenient time (suchas the middle of the night) while backing up individualcomputers can be complicated if they have beenswitched off or, in the case of laptops, disconnectedfrom the network and removed. The data on a singlefile server is also much easier to protect against theftor intrusion than multiple machines throughout theorganization.

Print ServerSignificant savings can be made by allowing manyusers to share a printer connected to a print server

instead of providing each user with his or her ownprinter. Typically, the roles of file server and print serv-er are combined into a single file-and-print server.

E-Mail ServerIn small organizations, e-mailis typically received and for-ward by a third party – usu-ally an Internet serviceprovider (ISP). Medium andlarge organizations frequent-ly run their own e-mail sys-tem – often MicrosoftExchange, IBM LotusDomino, or Open-Xchange –on a dedicated e-mail serv-er.

Other Roles• Web Server: making Web pages available over theInternet• Intranet Server: publishing information for internaluse within an organization

• Database Server: holding corporate informationfrom one or more corporate applications• Application Server: running applications that are



Working Out Your Server Requirments

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

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accessed by users with special client software runningon their personal computers, or simply via a Webbrowser such as Internet Explorer.

Form FactorForm factor is the term given to the overall size andshape of the server, which is determined by the caseor housing into which all the components are fitted.These include:

TowerIf you are only intending to buy a very small numberof servers, and are unlikely to need more, then atower form factor is probably the best choice. A serv-er with a tower form factor is a self-contained unit that

looks much like a standard desktop PC -- although itis likely to be slightly taller, allowing it to accommo-date as many as 10 disk drives.

In fact, there are a variety of tower form factors, whichin descending order of height include: Full tower, midtower, mini tower, micro tower.

Rack-Mounted ServerBigger organizations that require larger numbers of servers tend to choose a more compact and easy-to-manage rack mountable form factor. The standard

rack-mounted form factor is 19 inches wide, and 1.75inches deep, which is known as one unit, or simply1U. Servers and other equipment are made with adepth or thickness of multiples of 1.75 inches, so aserver may have a 1U, 2U, or even 6U form factor.

Rack-mounted servers are housed in a standard serverrack that is 42U high. A server rack can thereforehouse 42 1U servers, 21 2U servers, or combinationsof rack-mountable devices with a combined heightthat does not exceed 42U. Server racks usually con-

tain power supplies and efficient cooling systems todissipate the heat that such a large concentration of computing resources can produce.

The advantage of the rack-mounted server form factoris that large numbers of servers can be accommodat-ed in a small area of floor space. Rack mounting canalso significantly simply power and network cablingrequirements.

BladeSince the standard rack-mounted server form factor is1U, this is, in theory, the smallest form factor a rack-mounted server can have. In practice there are evensmaller servers, called blades, which can be rackmounted.

Blade servers are extremely thin, stripped downservers, which are fitted into a blade enclosure. Ablade enclosure may have a 10U form factor butcould contain 16 blades. The blade enclosure itself often contains components such as network adaptersand power supplies that are shared by all the bladesin the enclosure, allowing the blades to be made assmall as possible.

Operating System

While desktop computers use an end-user operatingsystem such as Microsoft Windows XP or Vista, or SUSELinux Enterprise Desktop, servers run operating sys-tems that are tailored to the special needs of servers.

In general, a server operating system is designed for:• Stability• Reliability• Security• Ability to offer services to multiple client machinessimultaneously


Choosing the Right Server[ ]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 Suitablethan small number

Form Factor Chooser



Your choice of operating system may be largely deter-mined by the use to which you intend to put the serv-er. For example, if you intend to use the server as a

mail server running Microsoft Exchange, you will needa Windows server operating system – either WindowsServer 2003 or Server 2008. Similarly, if you want torun the popular open-source Web server Apache, youwill need to run a Linux operating system such asSUSE Linux Enterprise Server or Ubuntu ServerEdition.

For less specific applications, such as running yourserver as a file server, the choice of operating systemis much wider. Even if the majority of desktop com-puters in your organization are running Windows

operating systems, the file servers can run:• Windows Server• Any flavor of Linux server operating system,• Mac OS X Server operating system (this can onlyrun on Apple Macintosh hardware, and would nor-mally only be run in an organization which usesApple Macintosh desktop computers.)• In very large organizations it may be preferable torun Unix operating systems such as SunMicrosystems's Solaris or HP's HP-UX.

In general, the main considerations that determinethe choice of server operating system are:

• Skill sets of your staff. If no one in your organiza-tion is familiar with Linux then it is not a practicalchoice• Total cost of ownership. Linux software is freelyavailable while Windows software involves bothserver and client access license fees. However,license fees are only a component – together withsupport -- of the total cost of ownership of a serveroperating system.• Compatibility with any applications you wish theserver to run.

ProcessorsLinux and Windows-based servers usually run onprocessors made by either Intel or AMD. It is possibleto run a server using a standard Intel or AMD desktopprocessor, but in practice it is more common to use amore powerful processor specifically designed for usein a server.

Intel Xeon Server ProcessorsIntel offers three lines of Xeon processors:

• 3000 sequence Dual or Quad core



Windows Linux Mac OS X Server Other

Predominantly a Suitable – Suitable if staff Not suitable Not suitableWindows environment, Windows Small have Linux skillssmall organization Business Server

2003 or WindowsSmall BusinessServer 2008

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

Predominantly Not suitable Possibly suitable SuitableMac OS X if IT staff haveenvironment Linux skills

Running a particular Depends on Depends on Depends on Depends onserver based application application application applicationapplication

Operating System Chooser



• 5000 sequence Dual or Quad core• 7000 sequence Dual or Quad core

In addition, it offers the very high-end Itanium 2 9000sequence

AMD Opteron Server ProcessorsAMD offers thee lines of Opteron processors• 1000 range• 2000 range - up to two per server• 8000 range – up to eight per server

Other ProcessorsLinux, and Sun's Solaris Unix-based operating systemcan also be run using Sun Microsystems's UltraSPARCprocessors.

StorageAll servers need a storage subsystem to hold theoperating system, applications, and data that they

need. This normally takes the form of one or morehard disks, and these can physically be located insidethe server case, or externally, connected to the serverby a cable or network connection.

The most common type of hard drives are:• Serial ATA (SATA) drives• Small Computer System Interface (SCSI) drives

SATA drives tend to be cheaper than SCSI drives, but


Choosing the Right Server[ ]Intel AMD Other

Small business Xeon 3000 sequence Opteron 1000 rangeDual or Quad core

Medium sized business / Xeon 5000 sequence Opteron 2000 rangestandard business Dual or Quad coreapplications

Large business / Xeon 7000 sequence Opteron 8000 range UltraSparc T1high performance Dual or Quad coredata or transactionintensive applications

Mission-critical Itanium 2 9000 UltraSparc T1 / T2high end computing sequence

Processor Chooser

Since one of the key attributes of a server discussed earlier is reliability, it followsthat the server's storage system must be

reliable. For this reason it is very common for aserver's hard disks to be configured using RAIDtechnology to introduce redundancy. Whendisks are configured in a RAID array, one or more disks can fail and be replaced (often with-out the need to shut the server or storage devicedown) without any data being lost.

RAID works by copying the contents of thedisks in an array to one or more others in thearray. When one disk fails and is replaced, thecontents of the failed disk can be rebuilt onto

the new disk from the content stored on theother disks. The capacity of a RAID array isalways less than the sum of the capacities of the disks that make up the array.

There are a number of types, or levels, or RAID,including:• RAID 1: mirrors the contents of one disk ontoanother (and sometimes more than one other).

continued

Redundant Array of Inexpensive (orIndependent) Disks (RAID)



SCSI drives are much faster, allowing a server to pro-vide services to clients much more efficiently in a busyenvironment.

Hard drives are commonly available in capacitiesranging from about 80GB up to 750GB or more.Larger capacities are often achieved by increasing theareal density (i.e., the bits per square inch) of thedisk's storage platters, and there is some evidencethat disks with very high areal densities are less reli-able than those with lower densities when used in anintensive server environment. Given this, is it wise tospecify a larger number of lower capacity disks (350 to500GB) than a few very high capacity disks (750GB+)

Internal Hard DrivesThe simplest storage option is to use hard drives fit-ted inside the server. Servers may sometimes housesix or more hard drives, giving a storage capacity of between 2 and 6 TB without RAID.

External Hard DrivesMany servers use storage disks that are physicallylocated outside the server case. Devices that provideexternal storage include:

• Direct Attached Storage (DAS): a device thatcontains one or more hard drives, connected to theserver.• Network Attached Storage (NAS): a device con-taining one more hard drives, connected to thesame LAN as the server. The server may have exclu-sive use of the NAS, or the NAS may be used byone or more other servers or client computers.

• Storage Area Network (SAN): a storage area net-work is actually a complex system which connectsan array of disks (or other storage devices) to a serv-er in a way that makes the storage look (to the serv-er) as if it is attached directly. They tend to beexpensive and the preserve of large companies.

When assessing your likely storage requirements con-sider:

• How much data you have now• How much new data you are likely to create everymonth



Storage ChooserInternal 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 NAS10TB to 100TB devices required devices required

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

Redundant Array of Inexpensive (orIndependent) Disks (RAID)

No data is lost as long as at least one disk isfunctioning. The capacity of the array is equalto the capacity of one disk; so two 500GB disksconfigured using RAID 1 result in an array witha capacity of 500GB.• RAID 5: the most common RAID level, RAID 5uses three or more disks in an array, and dis-tributes and copies the data across the disks insuch a way that no data is lost if a single diskfails.• RAID 6: this is similar to RAID 5, but can tol-

erate up to two disks failing without any databeing lost. I



Servers usually play an important role in a busi-ness, and if one or more is unavailable (i.e., isnot working) it can be anything from inconven-

ient to disastrous.

Asking the following questions may help you get anidea of the importance of server availability:• How costly would it be foryour business if a serverwere unavailable for an hour,a day, or a week?• How much time can youafford for a server to beunavailable?• How much time andmoney would it take to fixany problems caused by los-ing data if a server failedunexpectedly?

Depending on your answers,it may be worth paying apremium for a high-availabil-ity server system.These include:

• A hardened standalone server: this is a server thatis fitted with extra parts such as an extra power sup-

ply and RAID storage, making it more reliable thana normal desktop machine. Companies such as HPoffer fault tolerant memory subsystems with spare

memory modules, mirrored memory or hot-plug-gable RAID memory.• A server cluster: this involves two or more serversthat are linked together and to a shared storagedevice. Usually one server, or cluster node, is putinto operation, while the other waits as a standbymachine. If the standby machine sees that the other

has failed, it takes over theduties that the failedmachine was previously per-forming. Sometimes bothnodes in a cluster can workat the same time, but willtake over the duties of theother should it fail.• A fault tolerant server:

fault-tolerant servers aredesigned from the groundup to work continuously,even when components fail.They do this by duplicatingalmost all of their compo-nents, so that any or all of their vital parts can fail with-out causing the server to

stop operating. The components are "hot-swap-pable" so they can be replaced while the server isrunning, and software monitoring alerts administra-

tors when components are beginning to fail so theycan be swapped out as quickly as possible.



The Availability Question

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A hardened standalone server: this is a server that is fitted with extra partssuch as an extra power supply and RAID storage, making it more reliable than

a normal desktop machine.

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Comparison Chart



If you think you need more than one server, you may be able to cut your costs significantlythrough server virtualization – running two or more virtual servers on a single physical servercomputer.

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 Windowsserver 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 thesame 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 VMwareoffer a system suitable for larger organizations that can transfer the states of all the virtual serversto 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 MicrosoftWindows Server 2008 to their customers, and some vendors including HP and IBM are also offeringthe option of embedding VMware's ESX Server 3i virtualization product on their servers – on USBstorage or a flash memory card that can be inserted to start the virtualized environment. I

Server Virtualization

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 neveronly for very short periods

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

catastrophe

Technical measures Software needs Some applications may Software needs nono modification need modifying to modification

become cluster aware.

IT staff need to managecluster

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



Server Buyer’s ChecklistOptions

Server Role File and print serverMail ServerEmail serverWeb Intranet serverDatabase serverApplication serverOther server

Form Factor TowerRack mountedBlade

Operating System Windows Server 2003 or 2008Windows Small Business Server 2003 or 2008Linux ServerMac OS X ServerUNIX / other

Processor Intel XeonAMD OpteronSPARC / other

Storage SCSI or SATA disks+DASNAS

SAN

High availability features Redundant componentsCluster systemFault tolerant system

Management software Many options available

Service / warranty 1 year, 3 year, 5 year1 hour response, same day, etc



Management Software 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 applicationpatches 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 managementprocess. These products include HP's Insight Control and Microsoft's System Center family of managementproducts (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.

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