Compaq 307560-001 Compaq ProLiant 2500 Server Technology - Page 9

201A/1196 TECHNOLOGY BRIEF (cont.) ... Memory The ProLiant 2500 architecture is designed to use buffered Extended Data Out (EDO) RAM. The basic idea behind EDO RAM is to decrease cycle time for sequential accesses to the same RAM and in so doing, to allow for more memory bandwidth. EDO RAM has an output buffer that allows the memory chip to accept the next address while still holding the previous data result on the data bus. This concept is a refinement of Fast Page Mode (FPM) RAM and increases main memory performance, particularly for multiprocessor systems. In preliminary TPC-C Benchmark tests conducted at Compaq labs, performance of a singleprocessor system with a 256-Kbyte L2 cache and 256 megabytes of EDO RAM operating under Windows NT was as much as 16 percent higher than for the same system using FPM RAM. Performance of a dual-processor processor system with a 256-Kbyte L2 cache and 256 megabytes of EDO RAM was as much as 44 percent higher than for the same system using FPM RAM. These results were obtained using the TPC-C version 3.1 Benchmark test, Microsoft Windows NT 3.51, and SQL Server 6.5. The ProLiant 2500 comes standard with a 32-megabyte EDO DIMM in the first of four available DIMM slots on the processor board. Additional DIMMs may be installed one at a time. The slide-out processor board and pluggable memory modules make memory upgrades in the ProLiant 2500 simple. Compaq highly recommends the use of higher bandwidth EDO memory in the ProLiant 2500 to support the increased memory bandwidth requirement of SMP operation. Compaq offers ProLiant 2500 Memory Expansion Kits containing a single 32-, 64-, 128-, or 256-megabyte buffered EDO DIMM. The system is expandable to 1 gigabyte of ECC-protected memory using the 256megabyte buffered EDO DIMMs expected to be available in November 1996. For the benefit of customers who plan to standardize on FPM memory to reduce their inventory of service spares or customers who have already invested heavily in FPM DIMMs, the ProLiant 2500 supports use of buffered FPM DIMMs with a 4K refresh and combinations of buffered EDO and FPM DIMMs. Compaq has available four buffered FPM memory expansion kits developed for the Compaq ProLiant 5000 Server. Because memory in the ProLiant 5000 is interleaved, each of these kits contains four buffered FPM DIMMs rather than one. As the table below indicates, the ProLiant 2500 supports use of the DIMMs from three of the four ProLiant 5000 kits. Compaq Part No. 219282-001 219283-001 219284-001 219285-001 ProLiant 5000 Memory Expansion Kits Total Memory Kit Contents 64-MB 4 x 16-MB DIMMs 128-MB 4 x 32-MB DIMMs 256-MB 4 x 64-MB DIMMs 512-MB 4 x 128-MB DIMMs Memory Refresh 4K 4K 4K 8K Supported in ProLiant 2500 yes yes yes no Customers considering use of FPM DIMMs in the ProLiant 2500 need to be mindful that there is a performance tradeoff in doing so: FPM memory gives a memory bandwidth of 178 megabytes per second, while EDO memory gives a bandwidth of 267 megabytes per second. 9