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

[Michal Novotny <minovotn@xxxxxxxxxx>]

On 06/22/2010 07:43 AM, Michal Novotny wrote:
> 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 is the updated version of my patch to allow read-only CD-ROM 
devices as you had a good point that read-only is supported for CD-ROM 
IDE drives (but only for them).

> > > 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
I was able to make it working now and this functionality seems to be 
working now however I think that the preliminary check before the 
transfer itself is a good idea. As far as I had it implemented already I 
just did some modifications to allow CD-ROM IDE read-only drives and 
this is the updated version.
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

Attachment: xen-fix-restore-handling-for-ide-drives-and-memory.patch
Description: Text Data

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