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Appendix B: Memory configuration options

Memory sparing

Sparing allows for memory to be set aside to replace memory under use when a DIMM’s correctable error count has reached a specified threshold. Spared memory configurations do not provide redundant copies of memory and the system cannot continue to operate when an uncorrectable error occurs.

The DIMMs on each memory board must be installed in pairs. Each pair is referred to as a bank. A bank may consist of one rank (a pair of single-sided DIMMs) or two ranks (a pair of double-sided DIMMs). You can refer to “Installing DIMMs” on page 73 for instructions on how to install a DIMM on a memory board.

When the memory mode is set to maximum performance or maximum compatibility, the BIOS setup supports setting one rank aside to server as spare for each memory board. When the correctable error rate for a failing rank exceeds the error threshold for switching to spare, the contents of the failing rank are copied to the spare rank. At the completion of the copy, the failing rank is disabled and the spare rank is used in its place. The BIOS reports the failing rank with a SEL (system event log) event, updates the DIMM error LED on the memory board, and sends memory RAS (reliability, availability, and serviceability) commands to the BMC (baseboard management controller) to update the system memory state. The DIMMs with the failed rank are disabled on subsequent boots. The spare rank is no longer used for spare, but instead used as a system memory.

When the BIOS setup is configured for sparing, the largest rank is chosen to serve as the spare. This ensures that the contents of any failing rank fit on the spare rank. The amount of the available memory in the system is reduced by the size of the spare rank. If only one rank is available on a memory board, the system BIOS does not configure this rank as a spare.

The BIOS setup utility executes a memory test prior to configuring the memory in POST and when a memory board is inserted into the system during a memory hot-removal or hot-add operation.

To configure memory sparing:

1Do either option below:

• Run BIOS setup. See “Entering BIOS setup” on page 96. - or -

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Acer R910 manual Memory sparing, To configure memory sparing