Solaris Volume Manager Administration Guide

Understanding Submirror Status to Determine Maintenance Actions

The metastat command of Solaris Volume Manager reports status information on RAID 1 volumes and submirrors. The status information helps you to determine if maintenance action is required on a RAID-1 volume. The following table explains submirror states shown when you run the metastat command on a RAID-1 volume.

Table 10–3 Submirror States


State	Meaning
Okay	The submirror has no errors and is functioning correctly.
Resyncing	The submirror is actively being resynchronized. An error has occurred and has been corrected, the submirror has just been brought back online, or a new submirror has been added.
Needs Maintenance	A slice (or slices) in the submirror has encountered an I/O error or an open error. All reads and writes to and from this slice in the submirror have been discontinued.

Additionally, for each slice in a submirror, the metastat command shows the following:

Device: Indicates the device name of the slice in the stripe
Start Block: Indicates the block on which the slice begins
Dbase: Indicates if the slice contains a state database replica
State: Indicates the state of the slice
Hot Spare: Indicates that a slice is being used as a hot spare for a failed slice

The submirror state only provides general information on the status of the submirror. The slice state is perhaps the most important information to review when you are troubleshooting mirror errors. If the submirror reports a “Needs Maintenance” state, you must refer to the slice state for more information.

You take a different recovery action depending on if the slice is in the “Maintenance” state or in the “Last Erred” state. If you only have slices in the “Maintenance” state, they can be repaired in any order. If you have slices both in the “Maintenance” state and in the “Last Erred” state, you must fix the slices in the “Maintenance” state first. Once the slices in the “Maintenance” state have been fixed, then fix the slices in the “Last Erred” state. For more information, see Overview of Replacing and Enabling Components in RAID-1 and RAID-5 Volumes.

The following table explains the slice states for submirrors and possible actions to take.

Table 10–4 Submirror Slice States


State	Meaning	Action
Okay	The slice has no errors and is functioning correctly.	None.
Resyncing	The slice is actively being resynchronized. An error has occurred and been corrected, the submirror has just been brought back online, or a new submirror has been added.	If desired, monitor the submirror status until the resynchronization is done.
Maintenance	The slice has encountered an I/O error or an open error. All reads and writes to and from this component have been discontinued.	Enable or replace the failed slice. See How to Enable a Slice in a Submirror, or How to Replace a Slice in a Submirror. The `metastat` command will show an `invoke` recovery message with the appropriate action to take with the `metareplace` command. You can also use the `metareplace -e` command.
Last Erred	The slice has encountered an I/O error or an open error. However, the data is not replicated elsewhere due to another slice failure. I/O is still performed on the slice. If I/O errors result, the mirror I/O fails.	First, enable or replace slices in the “Maintenance” state. See How to Enable a Slice in a Submirror, or How to Replace a Slice in a Submirror. Usually, this error results in some data loss, so validate the mirror after it is fixed. For a file system, use the `fsck` command, then check the data. An application or database must have its own method of validating the device.