Re: [Xen-devel] [PATCH] Fix restore handling checks

[Michal Novotny <minovotn@xxxxxxxxxx>]

On 06/21/2010 08:04 PM, Keir Fraser wrote:
> On 21/06/2010 17:30, "Michal Novotny"<minovotn@xxxxxxxxxx>  wrote:
>
>    
> > Hi,
> > this is the patch to fix restore handling to implement some more checks
> > to support more checks than for UUID and name duplicity. This patch
> > basically disallows the migration/restore of IDE drives with the
> > read-only flag since this is not supported according to the ATAPI/IDE
> > specifications so we should disallow this for both domain creation and
> > domain migration/restore.
> >      
> What about CD-ROMs? This would break my test domain config, for example.
>
>    
Right, there's the exception for CD-ROMs according to the spec. I should 
implement this as well but read-only IDE disk devices are not supported 
according to the IDE specs.
> > This patch implements it for both create and
> > restore/migrate functionality.
> >
> > Also, the check whether the host machine does have enough memory
> > available for the guest has been implemented which can be the real issue
> > when you try to migrate a guest from one machine to another that is not
> > having enough memory for this guest. The guest memory gets transferred
> > but it fails to run so it's not running on either of those machines
> > (i.e. domain is not on the destination nor source host machine).
> >      
> Failed restore should get reported back to the host that is saving the guest
> state, and cause that machine to resume execution of the original VM. Does
> that not work for you?
>
> Possibly checking up front for available memory on the target is a good
> idea, but it shouldn't be *essential* if the error handling is up to par.
>
>   -- Keir
>    
It was not working but I'm still coping with some issues that are 
save/restore related so maybe this is the reason why I was unable to see 
this behaviour.
Michal

>    
> > I did try it with restore functionality now since I've been able to make
> > it working for save once so I'm currently using one save image for the
> > testing but unfortunately I'm having many issues with the common
> > migration and save functionality since I've been able to make it working
> > once to save it correctly. Fortunately the restores for this one
> > particular save image is working fine. I was also thinking about 2
> > concurrent migrations to the guest and/or save with the concurrent
> > migration and it should be the issue (although it's not been tested
> > because of reasons described above) since the domain gets created and
> > it's available in the XendDomain list (i.e. xc.domain_getinfo() list) so
> > it shouldn't be an issue here.
> >
> > Michal
> >
> > Signed-off-by: Michal Novotny<minovotn@xxxxxxxxxx>
> >      
>    
--
Michal Novotny<minovotn@xxxxxxxxxx>, RHCE
Virtualization Team (xen userspace), Red Hat


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