Making It Perform

One of the easiest ways to scale a system is to purchase the system with parts that are known to be able to support the current load and two to three years of anticipated growth. Factors such as the number of processors, the amount and type of memory, and the disk subsystem work together to determine the maximum capacity of the server. Careful choices here will allow you to get the most bang for your buck.

Never Over Clock the Processor on a Production Server

Never let the desire for performance overshadow the need for stability. No matter how tempting it might look on paper, never over clock the processor on a production server.

Choosing the Right Processor Type

There are many processors on the market today. Sixty-four bit processors have already hit the market and 32-bit processors are faster than ever. With 64-bit operating systems reaching the market it can be quite tempting to jump on the bandwagon of 64-bit processing. When you are faced with this decision it is critical to do the research and make sure it's the right decision. Don't be fooled by 64-bit processors and 64-bit operating systems. If the application isn't 64 bit the system will run it in a backwards compatible mode. More often than not this will result in slower performance than a high-end 32-bit processor. As more and more 64-bit applications are released this will become less and less of an issue.

Always Ask for Benchmarks and Let the Numbers Tell the Story

Not all 64-bit applications will take advantage of a 64-bit processor and operating system. Just because an application is ported to 64 bit doesn't mean that it is optimized for 64 bit. Always ask for benchmarks and let the numbers tell the story.

Eliminating Unnecessary Services

By reducing the number of unnecessary services running on a server the overall performance of the server can be enhanced. Services that need to be present but don't require a lot of resources can be tightly controlled by Windows System Resource Manager. A side benefit of removing unnecessary services is decreased exposure to security vulnerabilities. You should exercise common sense in determining what services should be removed. Although a Web server might not need the printer spooler service, it might still need the server service. More information on this type of tuning can be found in Chapter 23, "Tuning and Optimization Techniques."

Not All Memory Is Created Equal

Many of today's servers are using a type of memory known as DDR. DDR stands for Double Data Rate, which means that data can be transferred on both the upswing and downswing of the electrical cycle. This effectively doubles the speed of the memory. This speed is based on the front side bus speed of the motherboard, which in turn determines the speed of the processor. DDR memory is rated by the speed at which it is capable of running. For example PC3500 memory is capable of running at 433Mhz. The competing memory standard is RDRAM or RamBUS. RamBUS is also rated based on the speed at which it can run. For example RamBUS is offered as RamBUS1066. This runs at 1066Mhz and is designed to run with a system that supports a 533Mhz FSB. Not unlike processors, people tend to automatically associate clock speed with performance. This can be misleading because the real story is told by the memory bandwidth. RDRAM1066 is capable of 4.2GB/sec of transfer whereas PC3500 DDR is capable of 3.5GB/sec. Suddenly the gap has closed.

To further confuse the issue, memory is rated in terms of its latency. Most server memory is rated with a cache latency of 2.5. Memory with a cache latency of 2.0 is noticeably faster and will allow shrewd administrators to squeeze every ounce of performance from their servers.

If the Server Vendor Certifies the Memory, You Have Options

When purchasing memory for a server ask the server vendor if any other brands of memory are certified for use in his server. Oftentimes third-party companies produce memory that is faster and less expensive than the OEM memory from the server manufacturer. Think of the primary server manufacturers and ask yourself which of them are memory companies. If the server vendor certifies the memory, you have options.

Planning for Disk Subsystems

There are many ways to access disks on a server. Careful planning of the disk subsystem will enable you to take full advantage of space and performance now and enable you to scale storage and performance later as the need for additional capacity arises.

Current SCSI controllers are capable of up to 320MB of combined throughput. It is important to understand that this is the speed of the bus and not the speed of the SCSI drives . Unless the system is running multiple disks, an Ultra 320 controller isn't necessarily going to be faster than an Ultra 160 controller.

Fiber channel controllers have even greater throughput than SCSI controllers. Using Fiber channel to connect to locally attached drive arrays or Storage Area Networks can result in amazing disk IO performance.

Although IDE technologies have long lagged behind SCSI solutions, current generation Serial ATA drives offer very attractive pricing for excellent disk performance. Serial ATA RAID controllers (RAID 0,1,0+1) offer even better performance with the option of redundancy. For systems like Web servers in a Web farm, Serial ATA can be a very viable alternative to more costly SCSI drives.