Infortrend firmware functionality, configuration thru ... - ENEA AFS Cell

Figure 1 - 20 Logical Volume with 4 Logical Drives
Configuration B can help reduce the chance of encountering points
of failure:
a) Higher Redundancy: Configuration A has one dedicated spare,
while Configuration B allows the configuration of four spares. In
Configuration B, the risk of simultaneous drive failure in a logical
drive is significantly reduced compared to Configuration A. The
total array capacity is comparatively smaller by the use of spares.
b) Less Rebuild Time: The time during rebuild is a time of potential
hazard. For example, a RAID 5 logical drive can only withstand
single drive failure - if another drive fails during the rebuild
process, data will be lost. The time span for rebuilding a faulty
drive should be minimized to reduce the possibility of having two
drives 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 six
members will participate when rebuilding any of the logical drives.
c) Channel Failure Protection: Channel failure may sometimes
result from unlikely matters such as 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 avoid this point of failure.
Functional Description 1-13