HP Integrity rx4640 Server - Manual (Page 78)

Drive Arrays and Fault Tolerance
L4
L5
L3
A1
L1
L2
A2
Figure D-4: Two arrays (A1, A2) containing five logical
drives spread over five physical drives
Each logical drive in an array is distributed over all of the physical drives within the
array. A logical drive can also extend over more than one port on the same controller,
but it cannot extend over more than one controller.
Drive failure, although rare, is potentially catastrophic. In Figure D-4, for example,
failure of any physical drive causes all logical drives in the same array to fail, and all
data on the drives is lost.
To protect against data loss due to physical drive failure, logical drives are
configured with fault tolerance. There are several fault-tolerance methods; those
supported by current HP and Compaq branded controllers (and described in the
following section) are:
•
•
•
•
RAID 0—Data Striping only (no fault tolerance)
RAID 1+0—Drive Mirroring
RAID 5—Distributed Data Guarding
RAID ADG—Advanced Data Guarding
D-4 HP Smart Array 5300 Controller User Guide
HP CONFIDENTIAL
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