Memory Ras Features - Dell PowerEdge R940 Technical Manual

Memory RAS features

Reliability, Availability, and Serviceability (RAS) features help keep the system online and operational without significant impact to
performance, and decreases data loss and crashing issues. RAS helps in rapid and accurate diagnosis of system faults.
Table 8. Supported RAS features
Feature
Dense configuration optimized profile
Memory demand and patrol scrubbing
Recovery from single DRAM device failure (SDDC)
Failed DIMM isolation
Memory mirroring
Memory address parity protection
Memory sparing (rank)
Memory thermal throttling
18 Supported Memory
Description
Increased memory reliability can be a result from this selectable
platform profile that adjusts parameters to reduce faults regarding
refresh rates, speed, temperature and voltage.
Demand scrubbing is the ability to write corrected data back to the
memory once a correctable error is detected on a read transaction.
Patrol scrubbing proactively searches the system memory, repairing
correctable errors.
Recovery from Single DRAM Device Failure (SDDC) provides error
checking and correction that protects against any single memory
chip failure as well as multi- bit errors from any portion of a single
memory chip.
This feature provides the ability to identify a specific failing DIMM
channel pair, thereby enabling the user to replace only the failed
DIMM pair.
Memory mirroring is a method of keeping a duplicate (secondary or
mirrored) copy of the contents of memory as a redundant backup
for use if the primary intra-socket memory fails. The mirrored copy
of the memory is stored in memory of the same processor socket.
This feature provides the ability to detect transient errors on the
address lines of the DDR channel.
Memory sparing allocates one rank per channel as a spare. If
excessive correctable errors occur in a rank or channel, they are
moved to the spare area while the operating system is running to
prevent the errors from causing an uncorrectable failure.
This feature helps to optimize power/performance and can also be
used to prevent DIMMs from overheating.