Acer R910 Series ユーザーズマニュアル

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 Appendix B: Memory configuration options
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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: 
1
Do either option below:
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