[pve-devel] [PATCH 1/3] add live storage migration with vm migration

[Wolfgang Bumiller]

On Mon, Oct 17, 2016 at 03:33:38PM +0200, Alexandre DERUMIER wrote:
> >>considering some of the code looks like it's prepared for multiple
> >>disks, I wonder if the remote side should send a mapping containing the
> >>old + new names?
> 
> yes, I think it can prepare output for multiple disks, it'll be easier later.
> Maybe simply send multiple lines, 1 by disk ?
> 
> 
> 
> > + PVE::QemuServer::qemu_drive_mirror($vmid, $self->{target_drive}, $nbd_uri, $vmid); 
> > + #update config 
> 
> >>As far as I can see you have qemu running on the remote side already, 
> >>since you use hmp/mon commnads to export the nbd devices, so it seems 
> >>it would be a better choice to update this after the migration has 
> >>completed, and change the cleanup code below to detach the nbd drive. 
> 
> The problem is that when drive_mirror is finished, the source vm write to the remote disk.

So we'd need a way to switch back, then again the remote side might be
dead at this point... we could try though?

> So I think it's better to update config, to have the new disk in config.
> If source host die before end of livemigration, user only need to move the config file to destination host.
> 
> 
> Alternativly, I was thinking to use pending to store new local disk path, and switch at the end of the live migration.
> Maybe add a node=xxx option to drive during the migration, to known where the local disk is located exactly.
> I'm not sure...