I set up a Debian sarge amd64 (2.6.8 kernel) installation on a two-
disk Opteron machine with LVM on software RAID. The way I configured
things was to have one RAID1 mount /boot and the other serve as a
physical volume for LVM, which manages the rest of the filesystem,
including /.
In order to test the robustness of the system and practice
reconstructing the RAID, I powered down the machine, pulled a drive,
and booted up again. Everything came up fine, and /proc/mdstat
revealed that md0 and md1 each had a single disk.
I powered down again, added the disk, and powered up. Then I tried:
mdadm /dev/md0 -a /dev/sdb
The hot-add was successful, and /proc/mdstat revealed that /dev/md0
now included two disks.
Then I tried:
mdadm /dev/md1 -a /dev/sdb
Here's what this yielded:
md: trying to hot-add unknown-block(8,16) to md0 ...
md: could not lock unknown-block(8,16).
md: error, md_import_device() returned -16
mdadm: hot add failed for /dev/sdb: Invalid argument
From what I've read, this suggests that /dev/sdb is "busy", which
sort of makes sense considering that it's already participating in a
RAID1 on md0, but mdadm only supports commands affecting a single md.
I tried again with /dev/md1 first, thinking that LVM might be the
issue, but I get the reverse of the problem, where /dev/sdb is hot-
added successfully to /dev/md1 but cannot then be added to /dev/md0.
Is this expected behavior, or am I missing something?
--
Thomas F. O'Connell
Database Architecture and Programming
Co-Founder
Sitening, LLC
http://www.sitening.com/
110 30th Avenue North, Suite 6
Nashville, TN 37203-6320
615-469-5150
615-469-5151 (fax)
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