IBM ServeRAID, User Reference

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v If you are starting (booting) the operating system from a shared controller, define
the first logical drive as the startup drive and assign a merge-group number for a
non-shared drive, for example, 206 for Server A.
v The total number of logical drives per controller must be eight or less before or
after a failover. If you exceed this number, a failover will not be completed.
v The following logical drives will not failover:
– Logical drives currently undergoing Logical Drive Migration (LDM) operations
– RAID level-5E logical drives undergoing compression or decompression
– RAID level-5 or level-5E logical drives in a critical state
However, all other logical drives will failover if necessary.
v The ServeRAID controller does not permit the failover of RAID level-5 or level-5E
logical drives that are in a critical state. For this reason, do not use RAID level-5
or level-5E for the quorum drive. You must configure the quorum drive as a RAID
level-1 logical drive.
Note: Define hot-spare drives in your array to minimize the time that logical
drives remain in critical state.
v If a failover occurs while a critical RAID level-1, level-1E, level-10 or level-1E0
logical drive is rebuilding to a spare disk, the rebuild operation automatically
restarts.
v
The cluster support software will initiate a synchronization of all RAID level
logical drives except for the following:
– RAID level-0 logical drives
– Any critical or offline logical drives.
If a drive fails before this synchronization is complete, logical drive access is
blocked and is no longer accessible.
v
When a logical drive spans multiple SCSI channels and a failure within the drive
subsystem occurs that is unique to a channel (for example, a disconnected
cable), the entire physical array will be identified as failed even though access
from the surviving server can occur. Therefore, if you have small arrays, consider
not spanning multiple channels.
Chapter 12. Preparing to install or change a cluster solution
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