Intel SR6850HW4 - Server Platform - 0 MB RAM Product Manual page 41

The server BIOS also includes two additional memory reliability, accessibility, and serviceability
(RAS) features:
Memory Sparing: A rank on each memory board can be reserved as a "spare" and can only be
used as a backup for other ranks on the same memory board. The memory rank that is
configured as spare is held in reserve and cannot be used by the operating system. Hot removal
cannot be performed when in a Memory Sparing configuration.
When the error rate for a failing rank exceeds an established threshold, the contents of that rank
are copied to the spare rank. At the completion of the copy, the failing rank is disabled and the
spare is used in its place. This is called Memory Sparing. By enabling memory sparing, the total
memory of each memory board is reduced by the largest DIMM rank installed on the memory
board. This ensures that the any failing rank will fit on the spare rank.
When the failing rank switches to the spare, the BIOS will turn on the memory board LED to
indicate the bad DIMM. The failing DIMM is then disabled on subsequent system boots.
Memory Hot Plug: This memory RAS feature provides the ability to hot-replace and hot-add
memory boards while the system is running. This feature can be used to perform:
- Memory Hot Replace: While the system is in operation, you can remove a failed memory
board, provided it is in a RAID or Mirror configuration, and replace it with a board of the
same memory capacity. The system will test, initialize, and rebuild the data on the memory
board and then include this board in the system memory configuration. The activity is
transparent to the operating system,
- Memory Hot Add: You can increase the memory capacity of the system while the operating
system is active. In a RAID or Mirror configuration, you can remove one memory board at a
time to upgrade the memory or replace the memory board. In a Mirror configuration, you can
add an addition two mirrored memory boards. In a Maximum Compatibility configuration, a
new memory board can be added to an empty slot. When the initialization is complete, the
OS is informed of the new memory.
Memory Hot Add must be supported by the operating system in order to
perform this function. Check for an operating restrictions.
NOTE
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