Hi all,
This question is only slightly ontopic, in that the host system is a CentOS 5 box, but is otherwise a fairly generic question. I've looked in so many different places for an answer, but haven't had much luck, so I'm hoping someone here has some advice. (for the record: I posted this question to comp.os.linux.misc a few weeks ago)
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I made a minor mistake recently, and am trying to determine the cleanest way to clear it. Attached to my hardware RAID controller were two RAID6 units. One was the original disks that came with the server, which originally hosted our data, but had since had all its data migrated to a new LVM PV. The other is newer disks with a new PV, VG, and LV.
For testing purposes, after completing the pvmove I created a clean, new LV on the unit containing the old disks. (I believe that I actually destroyed the original RAID6 array and created a new one.) Unfortunately, I completely forgot about this LV during a recent hardware upgrade, and didn't run through the LVM steps to completely remove an unused physical volume before removing these old disks. (At least the LV was not mounted at the time). Now LVM seems to be confused about the disks and volumes that are available, and the kernel may also be confused.
Taken from a recent reboot, here's the dmesg log entry for the old testing unit:
sd 1:0:2:0: Attached scsi disk sdc
Later on, I removed the disks through the controller's tools, replaced them with new ones (so this is the third set of disks), and created a new RAID6 unit. After making the new unit I see (among other messages which don't seem helpful):
May 19 16:27:28 xxxx kernel: sd 1:0:2:0: Attached scsi disk sdd
Later on, when trying to run parted or friends, I see messages like so:
May 23 11:22:47 xxxx kernel: scsi 1:0:2:0: rejecting I/O to dead device
(note the same scsi address as sdc?)
And pvdisplay says:
# pvdisplay /dev/testVG/testLV: read failed after 0 of 4096 at 0: Input/output error
That looks bad--it seems like testLV is trying to find the old LVM on /dev/sdc, but the array on sdd is there instead. Worse, I fear that trying to manipulate sdd may cause problems in the future, so am wary of doing anything with it before I clear up this issue.
What should my next steps be? I've seen recommendations (in other somewhat similar situations) to try an lvscan or vgscan to refresh the list of volumes; or to try vgreduce --removemissing to remove the now-gone volumes from what LVM thinks is there. I do also still have the original disks, which I could put back and try to get LVM to re-find, but would be a pain. I am hoping to avoid a reboot, since the current LV seems unaffected and is in use, but I can do it if it's the surest way to make sure my LVM configuration is clean.
I should point out that I do not care at all about the data on testLV; all I want to do is cleanly tell LVM not to worry about that volume any more, and be in a position to use the third set of disks safely and reliably.
Thanks for reading--I hope you can help.
--keith