HP DL580 ProLiant DL580 Generation 4 Maintenance and Service Guide - Page 62

memory, the server is protected against uncorrectable memory errors that would otherwise result in server failure. Hot-plug mirrored memory allows the server to keep two copies of all memory data on separate memory boards. If an uncorrectable error is encountered, the proper data is retrieved from the memory board that did not fail. In addition, hot-plug mirrored memory allows failed or degraded DIMMs to be replaced while the server is running without requiring server downtime. The memory board with the failed DIMMs can be removed, failed DIMMs replaced, and the board re-inserted into the server without any interruption to the operating system. Hot-plug mirrored memory is supported with either two or four memory boards installed. No operating system support is required. Hot-plug mirrored memory has two configurations: dual-board and quad-board. Single-board mirrored memory is not supported. For either mode, choose "Mirrored Memory with Advanced ECC" in RBSU. The following guidelines apply to hot-plug mirrored memory: • All general memory requirements apply. • Hot-plug mirrored memory is supported with two or four memory boards. • Memory boards 1 and 2 are populated for dual-board hot-plug mirrored memory. Boards 1, 2, 3, and 4 are populated for quad-board hot-plug mirrored memory. Any deviation from these guidelines results in the server defaulting to Advanced ECC ("Advanced ECC memory" on page 60). • Memory boards 1 and 2 form a mirrored pair for dual-board hot-plug mirrored memory. For quad- board hot-plug mirrored memory, memory boards 3 and 4 also form a mirrored pair. • Memory boards within a mirrored pair must have the same amount of total memory. However, each board of the mirrored pair may have different DIMM configurations as long as they have equal total size. For example, memory boards 1 and 2 could each contain 2 GB of physical memory per board with board 1 containing two 1-GB DIMMs and board 2 containing four 512-MB DIMMs. • The amount of memory between mirrored pairs can be different in quad-board Hot-Plug Mirrored Memory mode. For example, memory pair 1 (boards 1 and 2) can contain 2 GB each while memory pair 2 (boards 3 and 4) contain 4 GB each. • In quad-board hot-plug mirrored memory, the two pairs of memory boards operate independently. One of the pairs of memory boards can be degraded while the other pair of memory boards can still be fully mirrored. • Hot-add operations are not supported. Board removals and insertions in Hot-Plug Mirrored Memory mode are solely for the purpose of hot-replace operations. • For hot-replace to function properly, the memory board must be re-inserted into the location from which it was removed. If the board is placed into the incorrect slot (for example, if board 2 is removed in dual-board mode and re-inserted into memory slots 3 or 4), a configuration error occurs. Attempting to insert a board into the improper position results in audio alarms and visual alerts. • Replace only one board at a time. That is, if memory boards 2 and 4 both contain memory errors, remove board 2, correct the error, and replace board 2. Wait for the board status LED to stop flashing before proceeding to board 4. • If a board is inserted into a valid memory slot but with an invalid DIMM configuration (including too much or too little memory), a DIMM configuration error occurs and a visual alert occurs (refer to Memory Board Components and LEDs (on page 79)). • If you remove a board while the server is running and do not replace the board, the server defaults to Advanced ECC ("Advanced ECC memory" on page 60) on the next reboot. Removal and replacement procedures 62