The aim behind disk scrubbing is to
repair bad sector of the disk automatically while system is in idle state
without compromising the performance. Oracle Exadata Storage Server Software
automatically inspects and repairs hard disks periodically when the hard disks
are idle.
The default schedule of scrubbing is
every two weeks.
Once a hard disk starts to develop bad
sectors, it is better to scrub that disk more frequently because it is likely
to develop more bad sectors.
In release 12.1.2.3.0, if a bad sector
is found on a hard disk in a current scrubbing job, Oracle Exadata Storage
Server Software will schedule a follow-up scrubbing job for that disk in one
week.
When no bad sectors are found in a scrubbing job for that disk, the schedule will fall back to the scrubbing schedule specified by the
When no bad sectors are found in a scrubbing job for that disk, the schedule will fall back to the scrubbing schedule specified by the
hardDiskScrubInterval attribute.
If the user has changed the
hardDiskScrubInterval to less than or equal to weekly, Oracle
Exadata Storage Server Software will use the user-configured frequency instead
of the weekly follow-up schedule even if bad sectors are found.
How to set
interval for disk scrubbing?
The
ALTER CELL hardDiskScrubStartTime command sets the start time for
proactive resilvering of latent bad sectors. Valid options are a date/time combination
or now.
Example:
CellCLI> ALTER CELL
hardDiskScrubStartTime='2013-08-07T21:19:22-07:00'
The
ALTER
CELL hardDiskScrubInterval command sets
the interval for proactive resilvering of latent bad sectors. Valid options are daily, weekly,
biweekly and none. Using the none option stops all disk scrubbing.
Example:
CellCLI> ALTER CELL hardDiskScrubInterval=weekly
The following table shows the
approximate time needed to scrub one idle hard disk:
In the alert log, you may see messages
such as "Begin scrubbing celldisk" and "Finished scrubbing
celldisk". These informational messages are expected, and no action is
necessary.
If the system is idle, disk scrubbing
can drive the disk utilization to 100%. This is expected. Disk scrubbing will
throttle itself using IORM based on disk activity. When requests come in, disk
scrubbing activity will decrease. Customer workloads should not be affected by
disk scrubbing.
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