Here I am, sitting in a test lab full of Intel-based serversabout a dozen systems ranging from a 400MHz Pentium II, to an eight-way Pentium III Xeon, to a just-released dual-processor 1GHz Pentium III. Now my father buys a 1.5GHz Pentium 4-based Dell Dimension desktop. Ack! I'm losing the MHz war to a retired guy!
Why doesn't this lab have a Pentium 4-based server? Simple, you can't get one. Hardware engineers at several large server manufactures say Pentium 4's limited performance, lack of supporting hardware, and high price have relegated the new chip to the desktop market. Because of these factors, Pentium III's reign over the server market continues.
The Pentium 4's first obstacle, the performance bottleneck, comes courtesy of the Pentium 4's Level 2 cache, which is a temporary repository for data fetched from main memory. The processor can retrieve information from the L2 cache much more quickly than it can grab information from memorybut if the cache is too small, not enough data can be stored in it, and thus the processor has to spend time waiting for the relatively slow memory subsystem.
The size of the L2 cache is one of the main performance indicators for a server. Intel's flagship server processor, the Pentium III Xeon, sports slower clock speeds (900MHz and 700MHz) than desktop system processors, but comes with extra-big caches of 1MB and 2MB. Several of the server experts I talked to said the Pentium 4's 256K L2 cache is too small for a server with clock speeds in excess of 800MHz. A server running at 1GHZ will show only modest performance increases over a server running at 800MHz. One expert cited internal testing of a server prototype running a 1.5GHz Pentium 4 vs. a 1GHz Pentium III. He said the ZD ServerBench tests results were almost identical.
The second challenge the P4 faces is the lack of a suitable chipset, which is one or more special-purpose chips that connect the processor with the PCI buses, memory, and disk controllers, and also allow multi-processor systems to share system resources. The two leading chipsets for servers are from Intel and ServerWorks, and neither company makes one that can handle multiple Pentium 4 processors, though both are preparing dual-processor chipsets suitable for servers. The only Pentium 4 chipset currently in production as of early June is Intel's 850, which is designed solely for single-processor workstations.
The final challenge is cost. Even if a server-class chipset did exist, a Pentium 4-based system would be considerably more expensive than a similar-performing server based on the Pentium III. The Pentium 4's reliance on expensive Rambus RDRAM also adds to the cost.
None of the server manufacturers I talked to expressed any interest in working with the current-generation Pentium 4 processor.
That may change, however, by the end of this year. Intel is rumored to be preparing a next-generation Pentium 4 for release between November and January, offering not only faster clock speeds of up to 2GHz, but also a 512K L2 cache. My sources at the server manufactures say the bigger cache alone should boost performance by 30 to 40 percent over a same-speed 256K version. ServerWorks is also expected to release a chipset that uses less-expensive SDRAM instead of Rambus' RDRAM.
All the signs say the next-generation Pentium 4 should be great for powering a server. I'll have to remember to invite my Dad over to take a look after I get one in early 2002.
Alan Zeichick is principal analyst at Camden Associates. A former systems analyst, value-added reseller, consultant, and tech journalist since 1984, Alan has been evaluating enterprise computing hardware and software systems for nearly two decades.