[Libvir] Is it possible to add an interface to intercept the migration process?

[Richard W.M. Jones]

Jack Meng wrote:
> Hi Richard,
> 
> Thanks for your reply.
> Actually I'm thinking about how to recognize the same storage (probably 
> external), not things on them. Sometimes storages are shared between 
> hosts but have different paths to access, e.g., for fibre channel 
> storages. So an update to the conf file is probably needed here to let 
> the dest attach 'right' storages.
> 
> Mirroring/iSCSI is not the case I'm considering.

I'm still a bit unclear about what you're trying to do.  Is the external 
storage mounted on the guest at the point when you're doing the 
migration?  If it is connected then you'd need to umount it before 
migration and mount it (with a new device name) afterwards.  Possibly an 
update to /etc/fstab would be in order too.  This seems to preclude live 
migration and requires cooperation from the guest during migration, so 
no special support by the HV is required.  You can just signal to the 
guest that it is about to be migrated and needs to do the umount/rename 
and wait until after it has been migrated to signal it again to remount.

If the external storage is actually your root filesystem then you are 
probably s.o.l at this point.

Rich.

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