Making the most of memory technology in SBS 2003 [Advanced Windows Small Business Server 2003 Best Practices]

Hiya – I am the co-author and publisher of the Advanced Windows Small Business Server 2003 Best Practices book and I love holding virtual book readings! Here is a passage 🙂

BTW – my SBS 2008 book is now here!

Making the Most of Memory Technology

Configuring a server or workstation is almost an art form. It requires a delicate balance between each component in order to optimize performance across the entire platform. In other words, why waste several thousand dollars on multiple gigabytes of memory if you’re using an 800 MHz Pentium III? In such a scenario, the processor invariably is going to bottleneck performance and no amount of RAM will change that, especially in an SBS 2003 environment where one machine performs numerous duties.

Along the same lines, it’s important that a Xeon or Opteron server have enough memory to avoid idle time. But it can be just as much of a challenge to buy for either platform as it is to buy for your cousin on the East coast who you see once a year at Christmas. To begin, both platforms require a special type of


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module called “registered memory,” which sacrifices some speed in the name of augmented reliability. Moreover, both processors interface with 128-bit memory buses for optimal performance. Because modern modules are 64-bits wide, it takes two identical pieces to populate the bus, in what is called a “dual- channel” configuration.

Because Opteron’s memory controller is located on the processor die itself, the chip enjoys very low latencies when accessing system memory. Unfortunately, that also means that adding support for cutting-edge memory technologies is more difficult. It’s of little consequence, though, as the Opteron performs very well with up to DDR400 RAM. Verify that whatever server you choose, it comes with registered modules installed in pairs.

Intel’s Xeon differs in that it supports the latest memory technology, DDR2, but doesn’t enjoy the same degree of throughput as Opteron. Xeon is also optimized for dual-channel operation with either DDR2 400 memory (400 referring to the frequency in megahertz) or DDR333. By virtue of its off-die controller, Xeon is more readily upgraded to forward-looking memory technologies.

The Pentium 4 is subject to many of the same constraints as Xeon, its pricier sibling, minus the registered memory requirement. It employs a 128-bit memory bus that interfaces with two modules rated at up to DDR2 533 speeds, yielding a maximum of 8.5 GB per second of bandwidth. Real-world numbers won’t ever get that high due to latencies in accessing the memory and the fact that the Pentium 4’s bus only moves at 800 MHz, transferring 6.4 GB per second. But it’s still highly flexible, with backward compatibility for DDR2 400, DDR400, and DDR333 modules.

 

 

AMD’s Athlon 64, on the other hand, has the same integrated memory controller as the Opteron, and as such is limited to DDR400, DDR333, or DDR266 modules. It apparently doesn’t matter though, as AMD’s own representatives claim that the processor is very sensitive to memory latency and its current support yields better performance than even the latest DDR2 memory technologies.

BEST PRACTICE: Be especially diligent when it comes to outfitting your server and workstations with memory. Most vendors aren’t specific in their use of single-channel and dual-channel implementations, and while the price difference isn’t significant (a


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single 1 GB module will cost roughly the same as two 512 MB modules), performance is impacted significantly. Whenever possible, be sure you’re utilizing your hardware to its fullest potential with dual-channel memory.

cheers….harrybbbb

Harry Brelsford, CEO at SMB Nation (www.smbnation.com)

MBA, MCSE, CNE, CLSE, CNP, MCP, MCT, SBSC (Microsoft Small Business Specialist)

PS – my Small Business Server 2008 (SBS 2008) book is now here!

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