Re: [Xen-devel] status of non-live migration of HVM with libvirt

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Mon, Jan 07, 2019 at 11:07:43AM +0100, Olaf Hering wrote:
> Am Fri, 4 Jan 2019 17:48:31 +0100
> schrieb Olaf Hering <olaf@xxxxxxxxx>:
> 
> > Am Fri, 4 Jan 2019 16:57:55 +0100
> > schrieb Olaf Hering <olaf@xxxxxxxxx>:
> > 
> > > worth keeping (and fixing) the concept of an "offline migration"  
> > 
> > And regarding the fix, it looks like qmp_xen_save_devices_state does not 
> > need the concept of "live". Just shutdown the blockdevices and be done with 
> > it?
> 
> Anthony, it looks like 5d6c599fe1 ("migration, xen: Fix block image
> lock issue on live migration") went too far. Why does stopping the
> disks at the very end of the save/migrate process depend on "live"?

Because "Snapshots don't need to inactivate images", see:
https://lists.xenproject.org/archives/html/xen-devel/2017-10/msg02782.html

I had to add the `live' parameter to fix the lock issue.

> During a migration the disks have to be released either way. During "xl save" 
> the domU may continue to run, if '-c' was specified. 

xl save -c is a snapshot, right? There isn't a second QEMU process that
is going to read/write the same disk.

> It seems the 'live' parameter for xen-save-devices-state is not needed.
> 
> Olaf



-- 
Anthony PERARD

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