On choosing the right server

Varied options exist. These range from Intel Xeon and AMD Opteron-based platforms to RISC-based machines

Servers are no longer as expensive as they used to be, and cost-effective processing is now available due to advances in silicon technology. Upgrading servers is a viable business proposition for an SMB. While there are many classes and platforms of servers, some basics remain the same.

The primary criterion to consider when assessing a server is your application requirements. This includes factors such as the number of users, application usage patterns, and hardware requirements of the software applications that you are running.

To start with, determine the number of users who will be accessing the applications that you wish to host on your new server. Without this being laid out, it is difficult to do server sizing. This process should be done considering future growth plans in terms of users and applications. If your company has expansion plans within the server’s expected lifecycle, this could well result in a greater number of users or the addition of application components. The chosen server should have the horsepower and be able to scale to handle these changes.

The hardware requirements should be dictated by the software and not the other way around. Application vendors tend to specify server configurations. These will include the platforms supported, minimum hardware required (budget for at least twice that), rule-of-thumb measures for the kind of hardware you need for a particular number of users, or some other parameters such as transactions per minute. Working with your system integrator will help determine an optimal server configuration.

Next comes an assessment of usage patterns. This will give an exact idea of the hardware required—number of servers, GB of memory and the kind of storage.

It has been observed that when the number of users simultaneously accessing a server exceeds 20, there is significant difference in the performance provided by a single processor (1-way) and dual processor (2-way) server with similar specifications. If the server is going to be accessed heavily on an extended basis (say, throughout the day), a 2-way or higher specification becomes necessary.

Redundancy helps

Availability is the next criterion. It is determined by the criticality of the application. How much downtime can be accommodated and how much cost can be incurred must be figured out.

This is where redundancy helps deliver availability. The more the server redundancy features, the higher the availability and associated costs. Redundancy is usually provided by means such as additional or hot swappable hard disks, power supplies, fans or hard disk drives in RAID configurations, ECC (Error Correction Code) RAM and load balancing.

If an application does not call for the costs incurred by providing high availability, a cost-effective configuration can be achieved by settling for few server redundancy options. The rule of thumb is to buy according to your requirements—not more, not less. That said, if you must err, do so on the side of overbuying, as insufficient power will choke your applications and thereby your business.

More than the processor

Look beyond the CPU. Your first priority should be memory. Don’t settle for less than 1 GB of RAM. DDR RAM is common on entry-level boxes, but it is better to go for DDR SD RAM if your budget permits. In fact, there are times when adding memory can improve performance far beyond the boost you would get by adding a processor. Redundancy by going in for ECC RAM is well worth the additional expenditure.

Hard disks come next on the checklist. Serial ATA (SATA) drives are an inexpensive alternative to SCSI. SATA and SCSI drives are available in speeds of 10,000 and 15,000 rpm. If redundancy is required, the option exists to connect drives in RAID-1 or three drives in RAID-5 configurations. Hot swappable hard drives give better availability as these can be replaced without downing the server, but these come at a premium.

Servers come in rack mount, blade and entry-level or workgroup boxes. It is important to choose the form factor according to the physical layout of your premises and the budget. The smaller the form factor (for example, 1U blade servers), the more expensive the server.

Product support options are available as 1-3 year onsite warranties covering parts and labour. Select the longest warranty tenure possible; it is possible to extend a warranty. The things to look for here are the coverage (is it just on weekdays or are weekends also included?) and the response time.

Servers can be classified by the number of processors. Common options for the SMB are 1-, 2-, 4- and 8-way servers. Based on the type of processor used, servers can be categorised into:

• x86 CPU-based (Xeon/Opteron/Pentium 4)
• Itanium 2-based
• RISC-based

The x86 genre

x86 servers built around Intel and AMD CPUs are available in 32- and 64-bit configurations, and these can go up to 8- or 16-way. Let us examine the 32-bit options first.

On the Intel range, the 32-bit options are Xeon, Xeon MP, Pentium 4 with hyper-threading and Pentium 4.

64-bit x86 processors are new entrants. Although 64-bit processors have been available from AMD for a while, they are still used in 32-bit mode for the greater part due to the lack of 64-bit operating systems. The recent release of 64-bit Windows Server 2003 ought to change the scenario soon.

For some time now, AMD has been a player in the 64-bit x86 server space, and it offers Opteron CPUs that are backward-compatible with 32-bit applications and can be used in up to 8-way servers. Intel’s got the 64-bit Xeon MP and Xeon processors.

Itanium 2

The Itanium processor family (IPF) is Intel’s 64-bit initiative that has spawned an entire class of servers. Unlike its predecessor, the Itanium, the Itanium 2 offers backward-compatibility with 32-bit applications.

The IPF includes the Itanium 2 multi-processor, Itanium 2 dual processor and Itanium 2 low-voltage variants. Itanium 2s are available in speeds ranging from 1-1.6 GHz and have 9 MB L3 cache.

RISC processors

Use of RISC processors in the SMB server space has been restricted to running core applications in medium businesses. This has been because of the high costs associated with these servers.

RISC servers are available from vendors such as IBM (POWER 5), HP (PA-RISC/Alpha), Sun (UltraSPARC) and SGI (MIPS). These processors are comparatively slower in terms of clock speed when compared to the x86 or Itanium platforms, but they are preferred for hosting applications such as core banking. The SMB space is dominated by x86 servers. With the increasing capabilities of these systems and their lower costs, they offer tough competition to RISC servers.

In the small business segment, x86 is the way to go. For mid-sized businesses, particularly in case of core applications, RISC is often the best bet.

newlypaul@networkmagazineindia.com