Re: [Xen-devel] Error checking on migration?

[Ewan Mellor <ewan@xxxxxxxxxxxxx>]

On Mon, Jun 05, 2006 at 09:50:06PM -0500, Anthony Liguori wrote:

> John Byrne wrote:
> >
> >I've noticed that migration doesn't fail if the VM cannot access the 
> >disk image on the new host. (xen-unstable 10273)  The VM ends up on 
> >the new host and hangs when it does a disk access. This is a somewhat 
> >evil behavior.
> 
> You could add some basic sanity checking in XendRestore.py:restore() 
> before xd.restore_() is invoked.  A consequence of doing device setup 
> through scripts is that the only proper way to know if a device creation 
> will succeed is by actually creating it.  It's further complicated by 
> the race condition that results by doing the checking before actually 
> grabbing the devices (what if another migration is in progress that 
> happens to use the same devices).

Also, migration to localhost is very useful for testing, so it's also 
complicated by the fact that the outgoing domain is using the devices
when the process starts, so you have to be careful to do the checks with
that in mind.

Ewan.

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