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.