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Capacity Coercion also affects a replacement drive used in a disk array. Normally, when an physical drive fails,
the replacement drive must be the same capacity or larger. However, the Capacity Coercion feature permits the
installation of a replacement drive that is slightly smaller (within 1 gigabyte) than the remaining working drive. For
example, the remaining working drives can be 80.5 GB and the replacement drive can be 80.3, since all are
rounded down to 80 GB. This permits the smaller drive to be used.
the replacement drive must be the same capacity or larger. However, the Capacity Coercion feature permits the
installation of a replacement drive that is slightly smaller (within 1 gigabyte) than the remaining working drive. For
example, the remaining working drives can be 80.5 GB and the replacement drive can be 80.3, since all are
rounded down to 80 GB. This permits the smaller drive to be used.
Without Capacity Coercion, the controller will not permit the use of a replacement physical drive that is slightly
smaller than the remaining working drive(s).
smaller than the remaining working drive(s).
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.
logical drive to zero. The action is useful because there may be residual data on the logical drives.
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.
will be lost. Backup any important data before you initialize a
logical drive.
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.
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.
Astra ES 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:
•
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 Astra ES.
•
Dedicated
– An unassigned disk drive that can only be used by a specified disk array.
The hot spare policy function lets you select whether a disk array will access any unassigned disk drive or a
designated drive in the event of disk drive failure.
designated drive in the event of disk drive failure.
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.
data onto the drive. When the rebuild is complete, the disk array is returned to fault tolerant status.
Astra ES 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.
When you create the hot spare drive, check the Revertible box to enable this feature.
Partition and Format the Logical Drive
Like any other type of fixed disk media in your system, a RAID logical drive must also be partitioned and
formatted before use. Use the same method of partitioning and formatting on a logical drive as you would any
other fixed disk.
formatted before use. Use the same method of partitioning and formatting on a logical drive as you would any
other fixed disk.
Depending on the operating system you use, there may or may not be various capacity limitations applicable for
the different types of partitions.
the different types of partitions.