Overview of Checking Status of RAID-5 Volumes
You can check the status of RAID-5 volumes by looking at the
volume states and the slice states for the volume. The slice state provides
the most specific information when you are troubleshooting RAID-5 volume errors. The RAID-5 volume
state only provides general status information, such as “Okay” or “Maintenance.”
If the RAID-5 volume state reports a “Maintenance” state, refer to the slice
state. The slice state specifically reports if the slice is in the “Maintenance”
state or the “Last Erred” state. You take a different recovery action depending
on if the the slice is in the “Maintenance” state or the “Last
Erred” state. If you only have a slice in the “Maintenance” state, it can
be repaired without loss of data. If you have a slice in
the “Maintenance” state and a slice in the “Last Erred” state, data has
probably been corrupted. You must fix the slice in the “Maintenance” state first, then
fix the “Last Erred” slice.
The following table explains RAID-5 volume states.
Table 14-1 RAID-5 Volume States
State |
Meaning |
|---|
Initializing |
Slices are in the process of
having all disk blocks zeroed. This process is necessary due to the nature
of RAID-5 volumes with respect to data and parity interlace striping. Once the
state changes to “Okay,” the initialization process is complete and you are able
to open the device. Until then, applications receive error messages. |
Okay |
The device is ready
for use and is currently free from errors. |
Maintenance |
A slice has been
marked as failed due to I/O or open errors. These errors were encountered
during a read or write operation. |
The following table explains the slice states for a RAID-5 volume and possible
actions to take.
Table 14-2 RAID-5 Slice States
State |
Meaning |
Action |
|---|
Initializing |
Slices are in the process of having all disk blocks
zeroed. This process is necessary due to the nature of RAID-5 volumes with
respect to data and parity interlace striping. |
Normally, none. If an I/O error
occurs during this process, the device goes into the “Maintenance” state. If the
initialization fails, the volume is in the “Initialization Failed” state, and the slice is
in the “Maintenance” state. If this happens, clear the volume and recreate it. |
Okay |
The
device is ready for use and is currently free from errors. |
None.
Slices can be added or replaced, if necessary. |
Resyncing |
The slice is actively being
resynchronized. An error has occurred and been corrected, a slice has been enabled,
or a slice has been added. |
If desired, monitor the RAID-5 volume status
until the resynchronization is done. |
Maintenance |
A single slice has been marked as failed due
to I/O or open errors. These errors were encountered during a read or
write operation. |
Enable or replace the failed slice. See How to Enable a Component in a RAID-5 Volume, or How to Replace a Component in a RAID-5 Volume. The metastat
command will show an invoke recovery message with the appropriate action to take with
the metareplace command. |
Maintenance/Last Erred |
Multiple slices have encountered errors. The state of the
failed slices is either “Maintenance” or “Last Erred.” In this state, no I/O is
attempted on the slice that is in the “Maintenance” state. However, I/O is
attempted on the slice marked “Last Erred” with the outcome being the overall
status of the I/O request. |
Enable or replace the failed slices. See How to Enable a Component in a RAID-5 Volume, or
How to Replace a Component in a RAID-5 Volume. The metastat command will show an invoke recovery message with the appropriate
action to take with the metareplace command. This command must be run with the
-f flag. This state indicates that data might be fabricated due to multiple
failed slices. |
