RE: [Xen-users] Safe iSCSI & Live Migrations

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

> I'm currently playing with iSCSI and Xen (exporting individual DomU
> block devices as individual iSCSI disks) and wanted to find a safe way
> to use iSCSI. i.e. I want to prevent the accidental mounting of an
iSCSI
> disk from two or more machines.  Using IET as an iSCSI target I can
set
> MaxConnections=1 in the config.  This ensures that no accidental
> filesystem corruption happens due to two or more simultaneous mounts.
> However live migration is out of the question.  To move a DomU from
one
> box to another with the MaxConnections=1 safeguard I have to;
> 
> Box 1:
> Shutdown the DomU.
> Perform an iSCSI logout.
> 
> Box 2:
> Perform an iSCSI login.
> Start the DomU.
> 
> Is there any way to perform a live migration of the above by getting
Xen
> to run iSCSI logout/login scripts as the DomU pauses in the middle of
> the live migration?  Are there any software hooks that can be used to
do
> this?
> 
> Or are there simpler methods to guarantee the safe/single use of iSCSI
> disks that still allow Xen's live migration?
> 

It sounds like Dom0 is making the iSCSI connection and exporting the
block device to DomU... is that the case?

If DomU initiated the iSCSI connection then I think this would solve all
of your problems, although it would create some of its own - root on
iSCSI can be a bit tricky.

James

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