Memory Ras Features; Table 9. Memory Ras Features - Dell PowerEdge R820 Technical Manual

Memory RAS features

RAS features help keep the system online and operational without significant impact to performance,
and can decrease data loss and crashing due to errors. RAS aids in rapid, accurate diagnosis of faults
that require service. Table 9 describes the RAS features supported on the R820.
Feature
Dense configuration
optimized profile
Memory demand and
patrol scrubbing
Recovery from single
DRAM device failure
Failed DIMM isolation
Memory mirroring:
intra-socket
Memory address parity
protection
Memory sparing (rank)
Memory thermal
throttling
For information on memory mirroring and sparing configurations, see the
Owner's Manual
on Dell.com/Support/Manuals.
19 PowerEdge R820 Technical Guide
Table 9. Memory RAS features
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
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, it is moved to the spare area while the operating
system is running to prevent the error from causing an uncorrectable failure.
This feature helps to optimize power/performance and can also be used to
prevent DIMMs from overheating.
Dell PowerEdge R820