[Ocfs2-users] OCFS2 and Xen interoperability issue

[Gonçalo Borges]

Hi All...

I'm testing a Xen solution on an OCFS2 SAN to store VM images,
and I'm observing an interoperability issue between two kinds of
softwares.

I've already tried to obtain some feedback from Xen experts without
any success. Maybe I'm more lucky on this list, and someone knows
a workaround to the problem.

The problem is the following: If I try to save a Virtual Machine (VM)
asking to store the checkpoint file in any local dir of the physical
host where the VM is running (ex: /tmp), everything works fine, and
I can properly restore the VM afterwards. Nevertheless, if I try to save
a VM asking to store the saved file inside the OCFS2 SAN, it fails with
the following messages in (xend) log:

---*---

[2009-08-21 14:45:25 xend 9720] INFO (XendCheckpoint:351) Saving memory
pages: iter 1   0%ERROR Internal error: Error when writing to state file
(5) (errno 14)
[2009-08-21 14:45:25 xend 9720] INFO (XendCheckpoint:351) Save exit rc=1
[2009-08-21 14:45:25 xend 9720] ERROR (XendCheckpoint:133) Save failed
on domain one-0 (9).
Traceback (most recent call last):
    File "/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
line 110, in save
      forkHelper(cmd, fd, saveInputHandler, False)
    File "/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py",
line 339, in forkHelper
      raise XendError("%s failed" % string.join(cmd))
XendError: /usr/lib64/xen/bin/xc_save 26 9 0 0 0 failed

---*---

It seems this is related to the fact that Xen is unable to "lock" the 
remote
block device, which in our case is an ocfs2 one. I'm not the only one 
complaining
about this issue, according to the following threads:

http://lists.xensource.com/archives/html/xen-users/2009-04/msg00670.html
http://lists.xensource.com/archives/html/xen-users/2008-09/msg00948.html

I wonder if anyone can provide additional info, or if there is some 
workaround
for the problem?

Cheers
Goncalo