I revived the broken Xencluster system a ... / 2010-09-14

I revived the broken Xencluster system again today. I managed to remove the 'clustered' attribute from VolGroup00 which contains the root filesystem. Based on Re: [Linux-cluster] iscsi and clusterd volume group on the redhat linux-cluster mailing list I again tried. I booted from the PLD linux rescue CD which has enough lvm parts. It saw VolGroup00 but would not let me do anything with it because it was clustered. The workaround was to enable lvm clustering with lvmconf --enable-cluster, edit the /etc/lvm/lvm.conf file (on the rescue cd ramdisk) to disable all locking (the dangerous option), locking_type = 0 after which I could disable the 'clustered' bit with vgchange -c n VolGroup00, revert /etc/lvm/lvm.conf to 'normal' and I had access to the volume group again, and a working system.