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HP ProLiant DL380 G3 - Identfying System Memory
PC2100 Compared to PC133
The ProLiant DL380 G3 supports up to six PC2100 DDR DIMMS running at 200MHz for a total of 6GB of memory. Although PC2100 SDRAM has the same data bus width (64 bits plus 8 ECC bits) as PC133 SDRAM used in earlier ProLiant servers, it has a higher effective data transfer rate because it transfers data twice per clock cycle. A 200MHz DDR system transfers data twice per 100MHz clock strobe. A PC133 system transfers data once per 133MHz clock.
In addition, column address strobe (CAS) latency on PC2100 DIMMs is 2.5, a half-clock faster than the CAS latency on PC133 DIMMs. Less latency means increased performance for the PC2100 DIMMs. Physically, the two DIMM types look different. The PC2100 is smaller—only 1.2 inches high compared to the 1.7-inch PC133. In addition, a PC2100 DIMM has a single notch in the gold connectors, and a PC133 DIMM has a double notch.
System Memory Subsystem
The ProLiant DL380 G3 supports up to six PC2100 DDR 200MHz DIMMs configured in three banks of two DIMMs. Each memory slot can support a 1GB DIMM, which brings the total maximum memory to 6GB. The ProLiant DL380 G3 memory subsystem has three banks. DIMMs 1 and 2 comprise Bank A, DIMMs 3 and 4 comprise Bank B, and DIMMs 5 and 6 comprise Bank C. DIMMs must be installed in pairs. DIMMs within a bank must be a matched pair. Bank A must be populated before Bank B, and Bank B must be populated before Bank C.
The ProLiant DL380 G3 incorporates DDR memory to improve memory performance. DDR memory doubles the number of data transfers per clock cycle by sending data on both the rising and falling edge of each clock signal. As a result, although the memory bus runs at 100MHz, it has the effective data transfer rate of a standard 200MHz bus.
Dual Interleaved Memory
The ProLiant DL380 G3 features dual interleaved memory. This technology uses identical 200MHz memory buses to double the amount of data obtained in a single memory access, from 64 bits to 128 bits. When a processor writes data to memory, the CMIC-LE, acting as the memory controller, distributes the data across both DIMMs in a bank. When a processor requests data, the CMIC-LE sends the request to both DIMMs simultaneously. Both DIMMs return a full cache line of data to fulfill the request. The CMIC-LE interleaves the data to return it to its original sequence.
In interleaving mode, each memory access transfers 144 bits—64 bits of data from each DIMM plus 8 bits for ECC from each DIMM. PC2100 SDRAM is designed to run on both 100MHz and 133MHz memory buses. On a 133MHz bus, DDR memory has the same transfer rate as a standard 266MHz bus.
Matching Data Transfer Rates
The memory subsystem of the ProLiant DL380 G3 can transfer data at 3.2GB/s using DDR PC2100 SDRAM DIMMs and dual interleaved memory. The Intel Xeon processor with 512KB L2 cache supports a quad-pumped 100MHz frontside bus. It transfers 64 bits of data four times per clock cycle, which also results in a data transfer rate of 3.2GB/s. Matching the data transfer rates of the memory and processor subsystems helps keep the processor pipelines full.
Standard models ship with 512-MB of PC2100 Registered DDR SDRAM Dual Inline Memory installed (2 x 256 MB SDRAM DIMM)
Standard Memory Replaced with Optional Memory
Up to 6,144-MB of memory is available with the removal of the standard 512-MB of memory and the optional installation of PC2100 Registered DDR SDRAM DIMM Memory Option Kit. You must observe the following guidelines when installing additional memory:
The DL380 G3 server ships standard with at least two 256 MB DIMMs installed in DIMM slots 1A and 2A.
Online Spare Memory
Online Spare Memory is a new high-availability feature on the Compaq ProLiant DL380G3 servers. Online Spare Memory will allow the server to continue operation should a DIMM begin to fail. When a pre-defined threshold for the maximum number of correctable ECC errors has been exceeded, Online Spare Memory will initialize the bank in standby – the spare bank – and will take over the failing memory bank. The server remains available during this process. The memory bank that exceeds the error threshold can be replaced at the customer's convenience during a scheduled shut down. During a scheduled shutdown, the failing DIMM is replaced with a functioning DIMM. When the server restarts, the memory banks resume their normal functions.
Online spare memory must be configured in RBSU. If you do not configure your server for online spare memory, all six slots can be used for main memory up to a maximum of 6GB. The spare bank is always the last bank populated. For example, if only Banks A and B are populated, then Bank B is the spare bank. If all three banks are populated, then Bank C is the spare bank. If you are using online spare memory with DIMMs in all six slots, then during startup the POST operation will only report the memory total of the DIMMs in the four slots being used. The DIMMs in the spare bank must be the same size as, or larger than, the other banks.
In the online spare mode, banks A and B provide standard memory functions, while bank C is configured for redundancy. DIMMs installed in bank C must be of equal or greater capacity than the largest pair of DIMMs installed in banks A or B. If any DIMMs in banks A or B exceed the limit for single-bit correctable errors, the system copies the memory contents of the failing bank to bank C; then, the system deactivates the failing bank. After installing DIMMs, use RBSU to configure the system for online spare memory support.
For more information on these new memory features see the Technology Briefs below (found on the Resources page):
Compaq Advanced Memory Protection Technologies
New Challenges Drive Compaq Advanced Memory Protection Strategy
NOTE: (Online Spare Memory) In the online spare memory configuration, the ROM automatically configures the last populated back as the spare memory. Therefore at least two banks of memory must be populated to enable spare memory. If only banks A and B are populated, bank B is the spare bank. If banks A, B, and C are populated, bank C is the spare bank, Online spare memory is configured through RBSU.
To configure online spare memory: