Re: [PATCH] Fix restore handling checks

[Michal Novotny <minovotn@redhat.com>]

On 06/21/2010 08:04 PM, Keir Fraser wrote:
> On 21/06/2010 17:30, "Michal Novotny"<minovotn@redhat.com>  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@redhat.com>
>>      
>
>    


-- 
Michal Novotny<minovotn@redhat.com>, RHCE
Virtualization Team (xen userspace), Red Hat