IBM 88554RU Installation Guide - Page 73

Both ports in a memory-board assembly must have the same total amount of memory. Partial mirroring is not supported. If the same total amount of memory is not detected at boot, memory mirroring is automatically disabled by the system. The DIMMs in partner banks across the two ports must be identical. You must install two pairs of DIMMs at a time. These four DIMMs (known as a bank) must be identical. Table 3-4 shows the pairs that are in each bank. Table 3-4 DIMMs that form a bank Bank DIMM pairs (see Table 3-3) 1 1 and 2 (DIMMs 1, 14, 15, 28) 2 3 and 4 (DIMMs 2, 13, 16, 27) 3 5 and 6 (DIMMs 3, 12, 17, 26) 4 7 and 8 (DIMMs 4, 11, 18, 25) 5 9 and 10 (DIMMs 5, 10, 19, 24) 6 11 and 12 (DIMMs 6, 9, 20, 23) 7 13 and 14 (DIMMs 7, 8, 21, 22) Hot-swap memory The hot-swap memory feature allows you to replace failed DIMMs without turning off the server. Hot-swap memory is operating system independent. The rules for hot-swap are as follows: Memory mirroring must be enabled in the Configuration/Setup utility. The configuration rules for memory mirroring apply here, specifically that the DIMMs in partner banks across the two ports must be identical. See "Memory mirroring" on page 58. When replacing a failed DIMM, you do not have to replace the other DIMM within the bank. Ensure that the new DIMM is the same type and size as the other DIMM within the bank. If a problem with a DIMM is detected, light path diagnostics will light the system-error LED on the front of the server, indicating that there is a problem and guiding you to the defective DIMM. When this occurs, first identify the defective DIMM and then remove and replace the DIMM. Chapter 3. Planning 59