Built to scale

If you're swapping files or applications over a small LAN and have no immediate plans for growth, a souped-up PC with a single Pentium III or Pentium 4 processor might be all you need in a server.But for high levels of reliability and expandability, you likely need a scalable server of the kind listed in this guide.These four-way or eight-way servers are powered by 700-MHz or 900-MHz Pentium III Xeon processors. Their scalability derives from the fact that you can begin with one or two processors and eventually build up the system to the allowable maximum of four or eight.The number of processors a server holds isn't the only measure of its scalability. Other factors include the amount of cache in each processor and the extent of expandable memory; the chip set and bus architectures; and the number of hard drives, expansion slots and drive bays.Reliability is a critical measure of server performance in environments where unexpected downtime can be disastrous. For mission-critical applications, look for built-in fault-tolerance, hot-swappable components and redundant power supplies.How do you want to protect your data? Most server operating systems provide some mirroring'in which data recorded on one hard drive is automatically copied onto another'but a better option is RAID within the server. You will have to pay more for a RAID controller and extra hard drives, but you'll sleep better if you have a good defense against the loss of mission-critical data.Also, consider buying a tape storage subsystem to supplement your server. Most manufacturers offer tape backup systems that are optimized for their products.By definition, scalable servers are highly customizable, so it is difficult to establish a baseline from which to compare different manufacturers' products. This is why the products listed in the chart vary in price so dramatically.Generally, it's up to you to 'spec out' the model you want and then ask for a price quote. In many cases, you can now configure and price a model you want on the manufacturer's Web site. Intel Pentium III Xeon processors scale well in four-way, eight-way and larger configurations. They are Intel's most advanced and powerful CPUs for midrange and back-end symmetric multiprocessing servers to date.Most four-way and eight-way servers use 700-MHz Pentium III Xeons, though a few, such as Dell's PowerEdge 8450 and Ion Computer Systems' Ion SRPM8, can also be outfitted with 900-MHz Xeons.Different versions of the Pentium III Xeon can support either 1M or 2M of Advanced Transfer cache and Layer 2 cache. They also support Intel's Dual Independent Bus design, which places the Level 2 cache on a dedicated high-speed cache bus and eases cache traffic on the system bus.Support for Intel's 64G Extended Server Memory Architecture also allows enterprise applications to use memory greater than 4G for enhanced system performance. A large cache lets a processor hold its own copy of the data it's using so it doesn't have to compete with other processors when accessing memory. Clearly, the larger the cache the better. The 700-MHz Xeon processor's 1M and 2M cache run at the same speed as the processor to enhance performance. Pentium III Xeon processors coexist with a variety of third-party chip sets, including those on Intel's four-way SRKA4 and eight-way SRPM8 server boards with the Profusion chip set for rackmount platforms. Most scalable servers use synchronous dynamic RAM with error-correcting code. Four-way systems allow up to 16G of SDRAM, and eight-way systems with the Profusion chip set allow for 32G of memory. Most servers listed in this guide come with an on-board, dual-channel SCSI controller for hard drives. A RAID controller is optional but must be included with a system that uses RAID. Many servers come standard with one or two hard drives but may be scaled up to 10 or more, depending on the drive bays provided. Ultra Wide2 SCSI and Ultra Wide2 low-voltage-differential SCSI drives are still popular in the server world, but faster Ultra160 drives are coming on strong. Drives range in capacity from 9.1G to 36G. If you're using RAID storage, the drives must all be the same size. The PCI bus architecture has become standard for servers, in both 32-bit and 64-bit types. The more expansion slots the better, so choose a model with six or eight slots. A high-speed 32X, 48X or 52X CD-ROM drive is essential for installing software on servers that generally don't require CD-rewritable drive capability. A 1.44M, 3.5-inch floppy drive is less important but will come in handy from time to time for legacy peripheral drivers or other necessities such as patches that arrive on floppy disk. A tower or pedestal case design generally offers the largest number of drive bay and expansion slots. On the other hand, a rackmount design is the most flexible, as many servers can easily be interconnected on the same rack. If system uptime is your first priority, paying extra for a server with hot-swappable components such as PCI slots and hard drives could prove well worth the money. A scalable multiprocessor server is inherently redundant, as one CPU can take over if another one fails. But server hardware redundancy also can be provided through double- or triple-redundant power supplies or redundant cooling fans. Many manufacturers offer an optional uninterruptible power supply with their servers. RAID data protection and tape subsystems should be included as options with any midrange or back-end server you buy. Most Pentium III Xeon servers support Windows NT Server, Windows 2000 Server and Windows 2000 Advanced Server. Many also support Novell NetWare, various flavors of Unix such as SCO UnixWare, and versions of Linux, such as Red Hat and SuSe. Sure, you need them, but they're the last items to worry about for high-end servers. Manufacturers know this and might not provide them unless you ask.XXXSPLITXXX-The Itanium architecture combines Intel's Explicitly Parallel Instruction Processing (EPIC) technology with 64-bit computational capacities, extending the limits of scalability and performance.Intel expects Itanium to compete with proprietary RISC architectures, which now command a leading share of the market for high-end servers.The EPIC design allows the processor to handle many operations in parallel and also includes technology to streamline executions and speed up applications.Intel officials say the Itanium architecture will process terabytes of data for high-level applications such as online transaction processing and electronic commerce.