On 10/22/2013 05:07 AM, Zhanghaoyu (A) wrote:
>
> NBD is used whenever both src and dst of migration is new enough to use it. That is,
libvirt >= 1.0.3 and qemu >= 1.0.3. The NBD is turned on by libvirt whenever the
conditions are met. User has no control over this.
> The advantage is: only specified disks can be transferred (currently not supported in
libvirt), the previous implementation was buggy (according to some qemu developers), the
storage is migrated via separate channel (a new connection) so it can be possible (in the
future) to split migration of RAM + internal state and storage.
Could you make a detailed statement for the buggy previous implementation, please ?
The bugs were in qemu, not libvirt; so you'll get a more complete answer
from the qemu list. I wish I knew enough details to give a better
answer, rather than just pointing you back to the other list; I just
know that the qemu developers recommended avoiding that mode of
migration with storage.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library
http://libvirt.org