Spare Drives Assigned To A Logical Volume; Figure 1 - 18 Logical Volume With Drives On Different Channels - Compaq External RAID Controller & Subsystem Infortrend Operation Manual

minimized to reduce the possibility of having two drives to fail at
the same time.
Configuration A is a large logical drive and takes a long time to
rebuild. All members will be involved during the rebuild process.
In Configuration B, the time span is shorter because only 6 members
will participate when rebuilding any of the logical drives.
c) Channel Failure Protection: Channel failure may sometimes
result from absurd matters like a cable failure. A channel failure
will cause multiple drives to fail at the same time and inevitably
lead to a fatal failure. Using a logical volume with drives coming
from different drive channels can get around this point of failure.
Figure 1 - 18 Logical Volume with Drives on Different
As illustrated above, should one of the drive channels fail, each
logical drive loses one of its members. Logical drives still have the
chance to rebuild its members. Data remains intact and the rebuild
can be performed after the failed channel is recovered. No access
interruptions to the logical volume will be experienced from the host
side.

Spare drives assigned to a logical volume?

A Local Spare can not be assigned to a Logical Volume. If a drive
fails, it fails as a member of a logical drive; therefore, the controller
allows Local Spare's assignment to logical drives rather than logical
volumes.
Functional Description
Channels
Logical
Volume
Logical Volume
24 drives, 4 redundancy drive
Configuration C - One logical volume with 4 logical drives
CH1 CH2
RAID 5
CH1/ID0 CH2/ID0
Logical
Drive
RAID 5
CH1/ID1 CH2/ID1
Logical
Drive
RAID 5
CH1/ID2 CH2/ID2
Logical
Drive
RAID 5
CH1/ID3
CH2/ID3
Logical
Drive
CH3 CH4 CH5 CH6
CH3/ID0 CH4/ID0 CH5/ID0 CH6/ID0
CH3/ID1 CH4/ID1 CH5/ID1 CH6/ID1
CH3/ID2 CH4/ID2 CH5/ID2 CH6/ID2
CH3/ID3 CH4/ID3 CH5/ID3 CH6/ID3
1-14