I suggest checking this from a dom0 perspective first before
continuing the hunt for weird and uncommon file system corruption
issues in the domU.
In the dom0, make sure your lvm is active, e.g. marked with an 'a'
rather than a 'd'
in the output of lvm lvs. I suspect you couldn't even get a disklabel
if it wasn't, but it can't hurt to check the lvm status in dom0 anyway.
I'd also suggest in dom0 dd'ing the lvm's raw device to /dev/null to
make sure there are no i/o errors.
lvs output, from the dom0, seems ok:
webserver vg1 owi-ao 20.00g
The `o'rigin attribute is set because I've just done a snapshot just in
case..
dd from the vbd to /dev/null went well also.
I have a bad feeling about this...