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Why do my software RAID devices not startup following system recovery?

Why do my software RAID devices not startup following system recovery?
After reinstalling my Red Hat system from a Storix backup, my RAID devices are not starting once the system reboots. During the bootup it says "Starting up RAID devices: md0(skipped).


ANSWER


The problem occurs because Red Hat's "rc.sysinit" script does a poor job of starting RAID devices. The original initrd that Red Hat used started all of the RAID devices in the linuxrc prior to running the rc.sysinit script. That is why the problem did not occur before Storix remade the initrd. The Storix initrd is only concerned with doing what is necessary to get the root (/) filesystem mounted.

The Red Hat rc.sysinit script first looks to /etc/raidtab to get a list of all of the RAID devices. Checks if they are active, and if not, tries to start them. It then looks inside /etc/fstab for the names of the RAID devices to start. If the RAID devices are not listed in /etc/fstab (which would be the case if you had LVM on top of RAID) the init script will skip those RAID devices. Hence, this is why you see the (skipped) message when the Red Hat init script is starting RAID devices.

To correct the problem with the RAID devices not starting, you can comment /etc/rc.d/rc.sysinit at lines 460-464:

------------8<------------
INFSTAB=`LC_ALL=C grep -c "^$i" /etc/fstab`
if [ $INFSTAB -eq 0 ] ; then
RESULT=0
RAIDDEV="$RAIDDEV(skipped)"
fi
------------8<------------

This has already been reported to Red Hat through Bugzilla as:

Bugzilla Bug 103407: rc.sysinit doesn't handle LVM on top of RAID