Dell External R720 T Technical Manual

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Dell External R720 T Technical Manual Manual pdf 26 page image

26 PowerEdge R720 and R720xd Technical GuideReliability, availability, and serviceability (RAS) features help keep the system online and operationalwithout significant impact to performance, and can decrease data loss and crashing due to errors.RAS aids in rapid, accurate diagnosis of faults which require service. Table 10 describes the memoryRAS features supported on the R720 and R720xd.Feature DescriptionIncreased memory reliability can be a result from this selectable platform profilethat adjusts parameters to reduce faults regarding refresh rates, speed,temperature and voltageDemand scrubbing is the ability to write corrected data back to the memory oncea correctable error is detected on a read transaction. Patrol scrubbing proactivelysearches the system memory, repairing correctable errors.Recovery from Single DRAM Device Failure (SDDC) provides error checking andcorrection that protects against any single memory chip failure as well as multi-biterrors 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 primarymemory fails. The mirrored copy of the memory is stored in memory of the sameprocessor socket.This feature provides the ability to detect transient errors on the address lines ofthe DDR channel.Memory sparing allocates one rank per channel as a spare. If excessive correctableerrors occur in a rank or channel, they are moved to the spare area while theoperating system is running to prevent the errors from causing an uncorrectablefailure.This feature helps to optimize power/performance and can also be used toprevent DIMMs from overheating.For information on memory mirroring and sparing configurations, see theDell PowerEdge R720 andR720xd Owner’s Manual on Support.Dell.com/Manuals. Memory RAID is not supported.