[PVE-User] shared LVM on host-based mirrored iSCSI LUNs
stsaenger at googlemail.com
Mon Apr 23 13:05:32 CEST 2012
after coping with the cluster problems I am back for another question.
Let me first describe the setup:
I have two small NAS boxes running openfiler each providing an iSCSI
LUN. These LUNs are exactly the same size.
I connected both LUNs to all three of my proxmox-servers (pve1, pve2 and
In order to implement host-based mirroring I installed mdadm on each
proxmox server and created a RAID1 on pve1 using both LUNs. (/dev/md0)
Then I created a physical volume on that RAID and a new volume group
After restarting mdadm and excuting pvscan the volume group was visible
on all 3 servers.
I added that volume group as a proxmox storage and set the "shared" flag
on the first server and then I installed / restored several virtual
machines to it using that volume group as storage.
And now I'm amazed because I did several tests with live migration,
adding VMs to HA, testing node failures etc.
Since I did not configure any locking for mdadm I figured that mdadm
would lead to corrupting the contents of the logical volumes used as
virtual hard disks.
But to my surprise fsck did not reveal any errors.
So my question is: Is there some locking already in place and I just
missed it? clvm is installed but obviously not used, /etc/lvm.conf is
set to file based locking and the locking_dir is local to every server,
Neither /etc/default/mdadm nor /etc/mdadm/mdadm.conf contain any hin
about locking, so I wonder if I only have been lucky not to encounter
any errors or if I missed something?
More information about the pve-user