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Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during n
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op |
Date: |
Wed, 10 Sep 2008 12:14:29 +0100 |
User-agent: |
Mutt/1.4.1i |
On Wed, Sep 10, 2008 at 02:11:56PM +0300, Avi Kivity wrote:
> Daniel P. Berrange wrote:
>
> >>This means that migration is no longer transparent. While migration is
> >>going on, you can't change the cdrom media, look at cpu registers, or do
> >>anything that requires the monitor.
> >>
> >
> >Changing cdrom media while in the middle of migration sounds like a rather
> >troubleprone thing todo - you'd need to change the media in both active
> >QEMU instances at the same time to be safe.
>
> Or rather, such state should be part of the migration. There's the
> question of whether to transform the path on the target, but "which
> media is in the drive" is part of the hardware state.
>
> (logically we would copy all of the data of all block devices, but
> that's not very practical, so we assume shared storage).
>
> What other commands are unsafe during migration? I exclude host device
> assignment which is obviously migration unfriendly.
USB + virtio device attach/detach - well at least have the same need as
media change - you'd need to propagate the change to the other side in
some way. Currently migrate just assumes the management tool/admin has
started QEMU on the destinations with the matching hardware config, and
for libvirt to use the monitor to add USB /virtio devices at both ends
has the race condition/synchronization problem .
Daniel
--
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- Re: [Qemu-devel] [PATCH 3/10] Add bdrv_flush_all(), (continued)
- Re: [Qemu-devel] [PATCH 3/10] Add bdrv_flush_all(), Glauber Costa, 2008/09/10
- Re: [Qemu-devel] [PATCH 3/10] Add bdrv_flush_all(), Anthony Liguori, 2008/09/10
- Re: [Qemu-devel] [PATCH 3/10] Add bdrv_flush_all(), Glauber Costa, 2008/09/10
- Re: [Qemu-devel] [PATCH 3/10] Add bdrv_flush_all(), Avi Kivity, 2008/09/10
- Re: [Qemu-devel] [PATCH 3/10] Add bdrv_flush_all(), Paul Brook, 2008/09/10
Re: [Qemu-devel] [PATCH 3/10] Add bdrv_flush_all(), Blue Swirl, 2008/09/12
[Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op, Anthony Liguori, 2008/09/09
Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op, Jamie Lokier, 2008/09/10
Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op, Avi Kivity, 2008/09/11
Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op, Jamie Lokier, 2008/09/11
Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op, Anthony Liguori, 2008/09/10
Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op, Chris Lalancette, 2008/09/10
Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op, Daniel P. Berrange, 2008/09/10
[Qemu-devel] [PATCH 10/10] TCP based live migration, Anthony Liguori, 2008/09/09