Compaq AlphaServer ES45 1B, Owner'S Manual

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Configuring and Installing Components 4-23
4.9 Memory Configuration
Become familiar with the rules for memory configuration before add-
ing the dual inline memory modules (DIMMs) to the system.
Memory Performance Considerations
Interleaved operations reduce the average latency and increase the memory
throughput over non-interleaved operations. With one memory option
(4 DIMMs) installed, memory interleaving will not occur. With two identical
memory options (8 DIMMs) installed, memory read-write operations are two-
way interleaved. With a minimum of four identical memory options (16 DIMMs)
installed, memory read-write operations are four-way interleaved, maximizing
memory throughput.
The output of the show memory command provides the memory interleaving
status of the system.
P00>>> show memory
Array Size Base Address Intlv Mode
--------- ---------- ---------------- ----------
0 4096Mb 0000000000000000 2-Way
1 1024Mb 0000000200000000 2-Way
2 4096Mb 0000000100000000 2-Way
3 1024Mb 0000000240000000 2-Way
10240 MB of System Memory
Stacked and Unstacked DIMMs
You can mix stacked and unstacked DIMMs within the system, but not within
an array. The DIMMs within an array must be of the same capacity and type
(stacked or unstacked) because of different memory addressing.
When installing sets 0, 1, 2, and 3, an incorrect mix will not occur. When in-
stalling sets 4, 5, 6, or 7, however, you must ensure that the four DIMMs being
installed match the capacity and type of DIMMs in the existing array (Model 1B
uses sets 0-3 only). If necessary, rearrange DIMMs for proper configuration.