Re: Live Migration, DRBD

[Dor Laor <dor.laor@qumranet.com>]

Kent Borg wrote:
> I am very happy to discover that KVM does live migration.  Now I am
> figuring out whether it will work for me. 
>
> What I have in mind is to use DRBD for the file system image.  The
> problem is that during the migration I want to shift the file system
> access at the moment when the VM has quit running on the host it is
> leaving but before it starts running on the host where it is arriving. 
> Is there a hook to let me do stuff at this point?
>
> This is what I want to do:
>
> On the departing machine...
>
>   - VM has stopped here
>   - umount the volume with the VM file system image
>   - mark volume in DRDB as secondary
>
>
> On the arriving machine...
>
>   - mark volume in DRBD as primary
>   - mount the volume with the VM file system image
>   - VM can now start here
>
>
> Is there a way?
>
>   
No, but one can add such pretty easy. The whole migration code is in one 
file qemu/migration.c
You can add a parameter to qemu migration command to specify a script 
that should be called on
migration end event (similar to the tap script).
> Thanks,
>
> -kb
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