Silicon Graphics InfiniteStorage 4000 Series, Configuring And Maintaining

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182 Routine Maintenance

Recovered media error
– The drive could not read the requested data on its first
attempt. The result of this action is that the data is rewritten to the drive and
verified. The error is reported to the Event Log.

Redundancy mismatches
– Redundancy errors are found, and a media error is
forced on the block stripe so that it is found when the drive is scanned again. If
redundancy is repaired, this forced media error is removed. The result of this
action is that the first 10 redundancy mismatches found on a volume are reported
to the Event Log.

Unfixable error
– The data could not be read, and parity information or
redundancy information could not be used to regenerate it. For example,
redundancy information cannot be used to reconstruct data on a degraded
volume. The result of this action is that the error is reported to the Event Log.
The script command set provides two commands to define media scan properties:
 set volume
 set storageArray
The
set volume
command enables a media scan for the volume. The command
has this form:
set (allVolumes | volume [ volumeName ] |

volumes [ volumeName1 ... volumeNameN ] |

volume < wwID >)

mediaScanEnabled=(TRUE | FALSE)
The
set storageArray
command defines how frequently a media scan is run on
a storage array. The command has this form:
set storageArray mediaScanRate=(disabled | 1-30)
The
mediaScanRate
values define the number of days over which the media scan
runs. Valid values are
disabled
, which turns off the media scan; or
1
day to
30
days, where
1
day is the fastest scan rate, and
30
days is the slowest. A value other
than what is shown will not allow the media scan to function.
Running a
Redundancy Check
Redundancy checks are performed when media scans are run. (For a description about
how to set up and run media scans, see “
Running a Media Scan
.“) During a
redundancy check, all of the data blocks in a volume are scanned, and, depending on
the RAID level, deteriorated data is corrected. Correction is performed as follows:

For RAID Level 3, RAID Level 5, or RAID Level 6 volumes, redundancy is
checked and repaired.

For RAID Level 1 volumes, the data is compared between the mirrored drives
and data inconsistencies are repaired.

RAID Level 0 volumes have no redundancy.
Before you can run a redundancy check, you must enable redundancy checking by
using the
set volume
command. The command has this form: