Solaris Volume Manager Administration Guide

Overview of Checking Status of RAID 5 Volumes

The slice state is perhaps the most important information when you are troubleshooting RAID 5 volume errors. The RAID 5 state only provides general status information, such as “Okay” or “Needs Maintenance.” If the RAID 5 reports a “Needs Maintenance” state, refer to the slice state. You take a different recovery action if the slice is in the “Maintenance” or “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 the “Last Erred” slice.

The following table explains RAID 5 volume states.

Table 14–1 RAID 5 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. Up to this point, 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 that 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 that 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, but I/O is attempted to 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, which must be run with the `-f` flag. This state indicates that data might be fabricated due to multiple failed slices.