HP ProLiant BL680c G7 Server-Blade - Manual (Page 56)

Hardware options installation 56
HP Memory Quarantine
The server blade is HP Memory Quarantine ready. The server blade will support this feature with a future
planned firmware upgrade. The operating system must support this mode. HP Memory Quarantine increases
the system availability by enabling the server and the operating system to work together to enable a server
to recover from uncorrectable memory errors that would have otherwise caused a system crash.
HP Memory Quarantine isolates the bad memory location before it affects other data. It does this by using a
patrol scrubber that constantly inspects the memory for errors. If an error is found, the hardware attempts to
correct it. If the hardware cannot correct the error, the operating system is notified. Then, the memory address
is tagged as bad so that the operating system does not use this memory location.
Online Spare memory population guidelines
Online spare memory provides protection against persistent DRAM failure. It monitors DIMMs for excessive
correctable errors and copies the content of an unhealthy rank to an available spare rank in advance of
multi-bit or persistent single-bit failures that may result in uncorrectable faults. Rank-sparing is more efficient
than DIMM-sparing since only a portion of a DIMM is set aside for memory protection.
When Online Spare memory is enabled, the first ranks of DIMM pair 4A/5A are set aside as the sparing
ranks. Therefore, the available memory is reduced by the size of the first ranks of DIMM pair 4A/5A.
If a DIMM rank on either of the SMI buses exceeds its correctable ECC threshold, then the contents of the
failing DIMM ranks are copied to the spare DIMM ranks. Once the copy is complete, all memory accesses
to the previous failing DIMM ranks go to the spare DIMM ranks.
No performance penalty occurs for rank-sparing, other than the time it takes to copy the data from the failing
rank to the spare rank upon an error condition.
The following population rules apply to each memory cartridge. Begin with the DIMM installation guidelines
(on page
49 ) with these additional constraints:
• All installed processors must contain a valid sparing configuration.
• If installing mixed rank DIMMs in a memory controller, follow the mixed rank installation rules of the
DIMM installation guidelines (on page 49 ).
• Rank sparing requires that the spare ranks of the DIMM pair 4A/5A be at least as large as any other
DIMM rank on the DDR3 channels of a memory controller. To determine the size of a single rank in a
DIMM, divide the total DIMM size by the number of ranks.
For example, the rank size of a dual-rank 2-GB DIMM is 1 GB and the rank size of a dual-rank 4-GB
DIMM is 2 GB. Therefore, it is possible to support rank sparing with mixed DIMM pair sizes on a
memory controller if the 4A/5A pair is populated with the 4-GB DIMMs and the other pairs are
populated with either the identical 4-GB or 2-GB DIMMs (all pairs on a memory controller are not
required to be populated). In this case, the 2-GB rank size of the 4-GB DIMMs in the 4A/5A pair is
equal to or greater than the rank size of the other installed DIMMs.
However, the server cannot support DIMM sparing in this example if the 2-GB DIMMs are populated in
the 4A/5A pair locations and the 4-GB DIMMs are populated in any of the remaining DIMM pair
locations on the same memory controller. This configuration violates the rule requiring that the spare
rank size of DIMM pair 4A/5A (1 GB) be equal to or larger than the single rank size of the other DIMM
pair locations, since the rank size of a 4-GB DIMM in pairs B, C, D, E, F, or G would be larger (2 GB)
than the spare rank size of the 2-GB DIMM pair in 4A/5A (1 GB).