On further investigation, it seems that something (multipath-tools? the kernel?) doesn't read the size of the underlying devices correctly. I initially thought this might be a problem with the GPT on the LUN I was using, but I was able to reproduce this problem on a new LUN.
I did the following: 1: I published a new LUN 22268000155ea65e2 to the server. The system saw it and multipath started correctly. 2: I partitioned /dev/mapper/22268000155ea65e2 with gdisk. 3: I created a new PV on /dev/mapper/22268000155ea65e2-part1, pvmoved everything off of the old PV (which I thought was on a disk with an invalid GPT), removed the old LV from the volume group and rebooted. 4: The same LVM symptoms I described initially occurred on reboot, and the kernel logged this: [ 44.081263] device-mapper: table: 254:1: dm-0 too small for target: start=2048, len=12638472159, dev_size=12638472159 [ 44.170954] device-mapper: table: 254:1: dm-0 too small for target: start=2048, len=12638472159, dev_size=12638472159 5: On the underlying volumes (e.g. /dev/sdi), gdisk reports no problems. On the multipath device, this happens: $ sudo gdisk /dev/mapper/22268000155ea65e2 GPT fdisk (gdisk) version 0.8.10 Warning! Disk size is smaller than the main header indicates! Loading secondary header from the last sector of the disk! You should use 'v' to verify disk integrity, and perhaps options on the experts' menu to repair the disk. Caution: invalid backup GPT header, but valid main header; regenerating backup header from main header. Warning! One or more CRCs don't match. You should repair the disk! Partition table scan: MBR: protective BSD: not present APM: not present GPT: damaged **************************************************************************** Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk verification and recovery are STRONGLY recommended. **************************************************************************** Command (? for help): v Caution: The CRC for the backup partition table is invalid. This table may be corrupt. This program will automatically create a new backup partition table when you save your partitions. Problem: The secondary header's self-pointer indicates that it doesn't reside at the end of the disk. If you've added a disk to a RAID array, use the 'e' option on the experts' menu to adjust the secondary header's and partition table's locations. Problem: Disk is too small to hold all the data! (Disk size is 12638472159 sectors, needs to be 12638474240 sectors.) The 'e' option on the experts' menu may fix this problem. Problem: GPT claims the disk is larger than it is! (Claimed last usable sector is 12638474206, but backup header is at 12638474239 and disk size is 12638472159 sectors. The 'e' option on the experts' menu will probably fix this problem Problem: partition 1 is too big for the disk. Identified 5 problems! Command (? for help): q I expect that I'll be able to produce a simple test case without LVM, but I'm still not sure what's actually at fault. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org