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On Tue, Feb 18, 2014 at 09:38:49AM +0000, Daniel P. Berrange wrote:
> On Mon, Feb 17, 2014 at 11:34:46PM -0700, Michael Still wrote:
> > Hi.
> > 
> > For the last day or so I've been chasing
> > https://bugs.launchpad.net/nova/+bug/1246201, and I think I've found
> > the problem... libvirt doesn't migrate devices of type cdrom, even if
> > they're virtual. If I change the type of the config drive to disk,
> > then block migration works just fine.
> > 
> > Does anyone know if this is a bug in libvirt? How would people feel
> > about me changing the type of config drives from cdrom to disk, which
> > is something that other hypervisors already do?
> 
> Be good to know what the reason was for it being set as a cdrom in the
> first place, before we change it to disk.

And here's that reason:

  commit 7f4b5771633f519a54aae985ae526418114b1a29
  Author: Tony Yang <bjyangf at cn.ibm.com>
  Date:   Thu Jul 18 18:45:24 2013 +0800

    Config drive attached as cdrom
    
    Some guest OSes (e.g. Windows) require config drive to be a cdrom device
    to access the iso9660 filesystem on it. Option config_drive_format is
    therefore set to also control the device type of config drive. If it's
    set to 'iso9660', config drive will be cdrom; if it's 'vfat', config
    drive will be disk.
    
    DocImpact
    Fixes: bug #1155842
    Change-Id: I6c08b1b8040a1fd0db8e2b3b1fc798060733001f

So I'd saying changing it to 'disk' is out of the question unless
we unconditionally use vfat as the filesystem instead of iso9660.

Regards,
Daniel
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