Product manual

Chapter 8: Technology Background
251
Initialization
Initialization is done to logical drives after they are created from a disk array.
Initialization sets all data bits in the logical drive to zero. The action is useful
because there may be residual data on the logical drives left behind from earlier
configurations. For this reason, Initialization is recommended for all new logical
drives. See “Initializing a Logical Drive” on page 120 (WebPAM PROe) or
page 163 (CLU).
Hot Spare Drive(s)
A hot spare is a disk drive that is connected to the disk array system but is not
assigned as a member of the disk array. In the event of the failure of a drive
within a functioning fault tolerant disk array, the hot spare is activated as a
member of the disk array to replace a drive that has failed.
VessRAID will replace a failing disk drive in a disk array with an unassigned drive,
if one is available. The unassigned drive is not part of any disk array. Such a drive
is called a hot spare drive. There are two types:
• Global – An unassigned disk drive available to any disk array on the
VessRAID.
• Dedicated – An unassigned disk drive that can only be used by a specified
disk array.
The hot spare policy function lets you choose whether a disk array will access
any unassigned disk drive or a designated drive in the event of disk drive failure.
See “Managing Spare Drives” on page 124 (WebPAM PROe) or page 159 (CLU)
for information on how to make this setting.
The spare drive effectively takes the place of the failed drive and the RAID
system immediately begins to rebuild data onto the drive. When the rebuild is
complete, the disk array is returned to fault tolerant status.
VessRAID includes a function that enables you to return a hot spare drive from a
disk array back to spare status. When you create the hot spare drive, check the
Revertible box to enable this feature. See “Transition” on page 261.
See also “Critical & Offline Disk Arrays” on page 290.
Caution
When you initialize a logical drive, all the data on the logical drive
will be lost. Backup any important data before you initialize a
logical drive.