Compaq Infortrend manual Spare drives assigned to a logical volume?

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 Channels

Logical Volume

RAID 5

Logical

Drive

RAID 5

Logical

Drive

RAID 5

Logical

Drive

CH1 CH2 CH3 CH4 CH5 CH6

CH1/ID0 CH2/ID0 CH3/ID0 CH4/ID0 CH5/ID0 CH6/ID0

CH1/ID1 CH2/ID1 CH3/ID1 CH4/ID1 CH5/ID1 CH6/ID1

CH1/ID2 CH2/ID2 CH3/ID2 CH4/ID2 CH5/ID2 CH6/ID2

Logical Volume

24 drives, 4 redundancy drive

RAID 5

Logical

Drive

CH1/ID3 CH2/ID3 CH3/ID3 CH4/ID3 CH5/ID3 CH6/ID3

Configuration C - One logical volume with 4 logical drives

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 1-14