Dell UCPM-800 manual Physical disk failure detection, Physical Disk Hot Swapping

Physical disk failure detection

Failed physical disks are detected and rebuilds automatically start to new disks that are inserted into the same slot. Automatic rebuilds can also occur with hot spares. If you have configured hot spares, the controllers automatically try to use them to rebuild failed physical disks.

Physical Disk Hot Swapping

NOTE: Shared PERC 8 supports physical disk hot-swapping, however this should only be implemented for unconfigured or failed drives.

Hot swapping is the manual replacement of a disk while the Shared PERC 8 card is online and performing the normal functions. The following requirements must be fulfilled before performing a hot swap of a physical disk:

•The replacement disk must be of the same protocol and disk technology. For example, only a SAS hard drive can replace a SAS hard drive.

•The replacement disk must be of equal or greater capacity than the one it is replacing.

Auto Replacement Of A Virtual Disk Member And Revertible Hot Spares

The automatic Replace Member functionality allows a previously commissioned hot spare to be reverted to a usable hot spare. When a disk failure occurs within a virtual disk, an assigned hot spare (dedicated or global) is commissioned and begins rebuilding until the virtual disk is optimal. After the failed physical disk is replaced (in the same slot) and the rebuild is complete, the Shared PERC 8 card automatically starts to copy data from the commissioned hot spare to the newly-inserted disk. After the data is copied, the new disk is a part of the virtual disk and the hot spare is reverted to a ready hot spare. This allows hot spares to remain in specific enclosure slots. While the Shared PERC 8 card is reverting the hot spare, the virtual disk remains optimal.

NOTE: The Shared PERC 8 card automatically reverts a hot spare only if the failed disk is replaced with a new disk in the same slot.

NOTE: A Replace Member operation typically has a temporary impact on disk performance. After the operation completes, the disk performance returns to normal.

Shared PERC 8 Card Cache Preservation

The Shared PERC 8 card is capable of preserving its cache in the event of a system power outage or improper system shutdown. The Shared PERC 8 card is attached to a Battery Backup Unit (BBU) that provides backup power to transfer contents of the DRAM to the Non-Volatile Cache (NVC) during system power loss.

NOTE: The Controller Cache Preservation feature is applicable only for virtual disks in write-back mode. Virtual disks in write-through mode do not have any data in cache.

Cache Preservation With Non-Volatile Cache

The Cache Preservation With Non-Volatile Cache (NVC) module allows controller cache data to be stored indefinitely. If the controller has data in the cache memory during a power outage or improper system shutdown, a small amount of power from the battery is used to transfer cache data to a non- volatile flash storage where it remains until power is restored and the system is booted.

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