User guide

48
10 Configure SAFE Volume Rebuild
Storage Policy
This SiI 4726 feature is provided to manage rebuilds of SAFE volumes.
When is a rebuild necessary?
A rebuild is initiated to restore data redundancy for a SAFE volume that has entered a vulnerable
state. In a vulnerable state, one of the two mirrored disks goes offline or is inaccessible. Although the
SAFE volume remains available during the rebuild process, the volume is susceptible to data loss
through damage of the remaining disk until data redundancy is restored through a rebuild. Host
access takes precedence over the rebuild process. If continuing to use the SAFE volume during the
rebuild, the rebuild process will take a longer time to complete.
Note: The rebuild feature also applies to other SAFE policies such as SAFE and BIG and SAFE and
FAST.
What happens during a rebuild?
The rebuild process restores data redundancy by first utilizing space allocated for a Hot Spare. In
case Hot Spare space does not exist or has already been rebuilt, the SteelVine processor rebuilds
to empty space on a hard disk drive other than the one containing vulnerable data. Following a
rebuild, it is not necessary to designate space to a Hot Spare for a subsequent rebuild to occur.
In this example, the daemon started a rebuild of Volume #1 after a failure of Disk #3. Once the
end-user replaces Disk #3 with a new hard disk drive, the SteelVine processor will initiate a
rebuild to Drive #3.