StorCase Technology InfoStation 5-Bay SATA 3Gbps RAID - Manual (Page 51)

InfoStation 5-Bay RAID User's Guide - Rev. C00 StorCase Technology, Inc.
RAID Configuration 41
Configuring SAFE Volume Rebuild Storage Policy
NOTE: The rebuild feature also applies to other SAFE policies, such as SAFE and BIG
and SAFE and FAST.
When is a rebuild necessary?
A rebuild is initiated to restore data redundancy for a SAFE volume entering a vulnerable state.
In a vulnerable state, one of the two mirrored drives 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 drive 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 longer to complete.
What happens during a rebuild?
The rebuild process restores data redundancy by first utilizing space allocated for a Hot Spare.
In the event Hot Spare space does not exist or has already been rebuilt, the InfoStation will
rebuild to empty space on a drive other than the one containing vulnerable data. Following
a rebuild, it is unnecessary to designate space to a Hot Spare for a subsequent rebuild to occur.
Once the Daemon rebuilds to a designated Hot Spare, the designated Hot Spare will not exist
and the InfoStation will rebuild to empty space on another drive.
With Automatic Rebuild and Immediate Rebuild options selected, the Daemon automatically
initiates an immediate rebuild. If the user wants the Daemon to delay the rebuild until after the
first write to the SAFE volume, select the Rebuild Only If Needed option. This allows
temporary removal of a drive without requiring a rebuild. To minimize the possibility of data
loss, the rebuild process should be set up to start immediately.
With Manual Rebuild selected, the user can decide when to initiate rebuild following a re-
build prompt. Unless the InfoStation is actively monitored, Automatic rebuild should be set
up to minimize the possibility of data loss.
In the event No is selected in response to a rebuild prompt, the user can select Scan Devices
from the File menu of the Status window to trigger a new prompt. If a power failure interrupts
a rebuild, the Daemon will restart the rebuild process.
Configuring a Rebuild
1. Select Specify Policy from the Edit menu of the Status window.