RE: [Xen-users] Save/Restore/Reboot FS Corruption

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> 
> Is it possible that anything modified the domain's virtual disks
during
> the "... time passes ..." section above?  Like maybe somebody mounted
a
> filesystem in the virtual disk from dom0 for some reason?  Or if
somebody
> accidentally did an xm create in the meantime?
> 

Just thinking out loud here, but how much work do you think it would be
to stop this happening for at least lvm backed devices?

lvchange has the ability to change an lv to not-available (basically
offline), or to read-only. Assuming these changes are persistent across
reboots of Dom0, an 'xm save' could set the lv to not-available after
the save is complete, and resume could check that it is in a
not-available state before changing it back to available and starting
the domain again. That would make sure nobody has inadvertently touched
the lv in the meantime. An 'xm create' would fail because the lv was not
available, as would any attempt to mount it. 'xm create' would need to
have a 'force' option to set the lv back to available again.

For file backed devices, you could just rename the backing file on save
and rename it back again on resume.

For physical disk backed devices I don't think there is such an easy
solution...

James

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