Background Information For Replacing and Enabling Slices in RAID 1 and RAID 5 Volumes

When you replace components in a mirror or a RAID 5 volume, follow these guidelines:

• Always replace components in the “Maintenance” state first, followed by those components in the “Last Erred” state.

• After a component is replaced and resynchronized, use the metastat command to verify the volume's state, then validate the data to make sure it is good. Replacing or enabling a component in the “Last Erred” state usually means that some data has been lost. Be sure to validate the data on the volume after you repair it. For a UFS, run the fsck command to validate the “metadata” (the structure of the file system) then check the actual user data. (Practically, users will have to examine their files.) A database or other application must have its own way of validating its internal data structure.

• Always check for state database replicas and hot spares when you replace components. Any state database replica shown to be in error should be deleted before you replace the physical disk. The state database replica should be added back before enabling the component. The same procedure applies to hot spares.

• RAID 5 volumes – During component replacement, data is recovered, either from a hot spare currently in use, or using the RAID level 5 parity, when no hot spare is in use.

• RAID 1 volumes – When you replace a component, Solaris Volume Manager automatically starts resynchronizing the new component with the rest of the mirror. When the resynchronization completes, the replaced component becomes readable and writable. If the failed component has been replaced with data from a hot spare, the hot spare is placed in the “Available” state and made available for other hot spare replacements.

• The new component must be large enough to replace the old component.

• As a precaution, back up all data before you replace “Last Erred” devices.

A submirror or RAID 5 volume might be using a hot spare in place of a failed component. When that failed component is enabled or replaced by using the procedures in this section, the hot spare is marked “Available” in the hot spare pool, and is ready for use.