Memory options 71
•
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
68
).
•
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
9
)).
•
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
68
) on the next reboot.
Hot-plug RAID memory
Hot-plug RAID memory provides a similar level of memory protection as hot-plug mirrored memory (on
page
70
) but obtains this protection using less total memory. Hot-plug RAID memory protects the server
against uncorrectable memory errors that would otherwise result in a server failure.
Although hot-plug mirrored memory keeps two copies of all memory data, hot-plug RAID memory keeps
only one copy of all memory data and additional parity information. If an uncorrectable memory error is
encountered, the server can create the proper data using the parity information and the information from
the other memory boards that contain no failures. In a hot-plug RAID memory configuration, 25% of the
installed memory is not available to the operating system. In a hot-plug mirrored memory configuration,
however, 50% of the installed memory is not available to the operating system.
