Silicon Graphics InfiniteStorage 4000 Series, Configuring And Maintaining, Page: 193 / 276

Chapter 11: Maintaining a Storage Array 181
11
Maintaining a Storage Array
Maintenance covers a broad spectrum of activity with the goal of keeping a storage
array operational and available to all hosts. This chapter provides descriptions of
commands you can use to perform storage array maintenance. The commands are
organized into four sections:

Routine maintenance

Performance tuning

Troubleshooting and diagnostics

Recovery operations
The organization is not a rigid approach, and you can use the commands as
appropriate for your storage array. The commands listed in this chapter do not cover
the entire array of commands you can use for maintenance. Other commands,
particularly the
set
commands, can provide diagnostic or maintenance capabilities.
Routine
Maintenance Routine maintenance involves those tasks that you might perform periodically to
make sure that the storage array is running as well as possible or to detect conditions
before they become problems.
Running a Media
Scan
Media scan provides a way of detecting drive media errors before they are found
during a normal read from or write to the drives. Any media scan errors that are
detected are reported to the Event Log. The Event Log provides an early indication of
an impending drive failure and reduces the possibility of encountering a media error
during host operations. A media scan is performed as a background operation and
scans all data and redundancy information in defined user volumes.
A media scan runs on all of the volumes in the storage array that have these
conditions:

Has Optimal status

Has no modification operations in progress

Has media scan enabled
Errors that are detected during a scan of a user volume are reported to the Major
Event Log (MEL) and handled as follows:

Unrecovered media error
– The drive could not read the requested data on its
first try or on any subsequent retries. The result of this action is that for volumes
with redundancy protection, the data is reconstructed, rewritten to the drive, and
verified, and the error is reported to the Event Log. For volumes without
redundancy protection, the error is not corrected, but it is reported to the Event
Log.