Re: [Qemu-devel] Live Migration with different block devices

[Xiongzi Ge]

Hi ,

This is just related to migration, but it may be not in the standard migration.  The cache device in different hosts can only be accessed by the vm running in the host.  The problem for me is to find the interface of the cache in the guest or like first doing it in the qemu, after migration, this cache should recognize that the cache content storing in the disk has been changed.   DOes anyone has good suggestions? Thanks ! 

On Tue, Jun 24, 2014 at 4:41 PM, Eric Blake <address@hidden> wrote:

On 06/24/2014 01:55 PM, Xiongzi Ge wrote:
> Hi Paolo,
>
> I am trying to do migration with two different block devices in the source
> and destination hosts.  For example, in the source the data in /dev/vda
> are  'aaaaa'. The guest has a cache. These data are cached.  In the other
> host, the data in this device are 'bbbbb'.   If we do migration, I want
> the  guest vm recognize this change.  How does qemu deal with the cache
> data?  Thanks.

If you want the guest to see different disk contents, then hotunplug the
original and hotplug in the new disk.  Migration is NOT supposed to
change disk contents.  Your problem is independent of migration.

--
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org