[Cialug] RAID Reshaping

[L. V. Lammert]

In case anyone else runs across this thread:

The reshaping took about 20 reboots over three days, but the last 30% went
pretty fast.

1) Reshaping does require exclusive access to the unmounted array;
anything else is asking for problems. As reboots seems to be common, after
the first one I disabled that volume in fstab.

2) After a crash (and reboot), it took a some time for the array to
recover (i.e. change to "Active"); did not time it, just let it sit for
15-20 minutes after reboot. I assume it was replaying the journal?

Once Active, however, reshaping did not resume.

3) Continuing the reshaping process required the following sequence:

2a) Mount the file system
2b) Immediately unmount the file system

Watch mdstat to verify status, and log out.

3) When the process finally completed, I started an xfs_repair on the
partition, logged out and let it run.

4) After a few hours it was complete, and a quick xfs_growfs -d <mounted
filesyetem> took about 30 seconds. Voila`, `15T -> 22T.