Re: [Qemu-block] [Qemu-devel] [PATCH COLO-Block v6 07/16] Add new block driver interface to connect/disconnect the remote target

[Wen Congyang]

At 2015/6/23 21:42, Stefan Hajnoczi Wrote:
> On Mon, Jun 22, 2015 at 09:56:24PM +0800, Wen Congyang wrote:
> > > The NBD connect should not be performed during downtime, regardless of
> > > whether a monitor command is used or not.
> >
> > Why?
>
> NBD connection establishment takes unbounded time.  It can extend the
> downtime period and cause users to notice that the guest is unavailable.
>
> The point of COLO is fault tolerance and high availability.  In order to
> achieve that, COLO must minimize downtime.  If an operation can be
> performed outside the migration downtime phase, then it should be done
> outside.

Yes, you are right. I will think about it.

Thanks
Wen Congyang

> Stefan