IT Infrastructure blog

May 23, 2011

Disk Scrub in NetApp

Filed under: NetApp — Akther @ 10:46 pm
Tags: ,

Have you noticed this autosupport email from netapp box?  And there is no action required from storage admin side? quite interesting….

System Notification from FAS270 (DISK SCRUB SUMMARY – no customer action required) INFO

NetApp use disk scrubbing to protect data from media errors, or bad sectors, on a disk. Each disk in a RAID group is scanned for errors. If errors are found, they are fixed by reconstructing data from parity and rewriting the data. Without this process, a disk media error might cause a multiple disk failure while running in degraded mode.

Automatic RAID scrub is enabled by default .

You can also manually start and stop disk scrubbing regardless of the current value (on or off) of the  raid.scrub.enable option.

Degraded Mode

When there is a single-disk failure in a RAID-4 raid group or a double-disk failure in a RAIDDP raid group and there are no hot spares available, the system will operate in “degraded” mode for a period of time. The default is 24 hours. You may want to set this to a longer time interval(by using the options raid.timeout command) if access to the system is limited for a specified period, such as a long weekend.

No data is lost in degraded mode, although the system will not perform optimally. But if the failed disk is not replaced during this period, the system will shut down.

be careful about using the  options raid.timeout command to lengthen the time the system will operate in degraded mode before shutdown, because a longer interval increases the risk of a second disk failure and resulting data loss.

Thanks

Akther

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