RE: [PATCH v2 3/4] build: move COLO under CONFIG_REPLICATION

[Zhang, Chen]

> -----Original Message-----
> From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> Sent: Friday, April 21, 2023 4:36 PM
> To: Zhang, Chen <chen.zhang@intel.com>; qemu-devel@nongnu.org
> Cc: qemu-block@nongnu.org; michael.roth@amd.com; armbru@redhat.com;
> eblake@redhat.com; jasowang@redhat.com; quintela@redhat.com; Zhang,
> Hailiang <zhanghailiang@xfusion.com>; philmd@linaro.org;
> thuth@redhat.com; berrange@redhat.com; marcandre.lureau@redhat.com;
> pbonzini@redhat.com; dave@treblig.org; hreitz@redhat.com;
> kwolf@redhat.com; lizhijian@fujitsu.com
> Subject: Re: [PATCH v2 3/4] build: move COLO under CONFIG_REPLICATION
> 
> On 21.04.23 06:02, Zhang, Chen wrote:
> >
> >
> >> -----Original Message-----
> >> From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> >> Sent: Thursday, April 20, 2023 6:53 AM
> >> To: qemu-devel@nongnu.org
> >> Cc: qemu-block@nongnu.org; michael.roth@amd.com;
> armbru@redhat.com;
> >> eblake@redhat.com; jasowang@redhat.com; quintela@redhat.com;
> Zhang,
> >> Hailiang <zhanghailiang@xfusion.com>; philmd@linaro.org;
> >> thuth@redhat.com; berrange@redhat.com;
> marcandre.lureau@redhat.com;
> >> pbonzini@redhat.com; dave@treblig.org; hreitz@redhat.com;
> >> kwolf@redhat.com; Zhang, Chen <chen.zhang@intel.com>;
> >> lizhijian@fujitsu.com; Vladimir Sementsov-Ogievskiy
> >> <vsementsov@yandex- team.ru>
> >> Subject: [PATCH v2 3/4] build: move COLO under CONFIG_REPLICATION
> >>
> >> We don't allow to use x-colo capability when replication is not
> >> configured. So, no reason to build COLO when replication is disabled,
> >> it's unusable in this case.
> >
> > Yes, you are right for current status. Because COLO best practices is
> replication + colo live migration + colo proxy.
> > But doesn't mean it has to be done in all scenarios as I explanation in V1.
> > The better way is allow to use x-colo capability firstly, and separate
> > this patch with two config options: --disable-replication  and --disable-x-
> colo.
> >
> 
> But what for? We for sure don't have such scenarios now (COLO without
> replication), as it's not allowed by far 7e934f5b27eee1b0d7 (by you and
> David).
> 
> If you think we need such scenario, I think it should be a separate series
> which reverts 7e934f5b27eee1b0d7 and adds corresponding test and
> probably documentation.

In the patch 7e934f5b27eee1b0d7 said it's for current independent disk mode,
And what we talked about before is the shared disk mode.
Rethink about the COLO shared disk mode, this feature still needs some enabling 
works.
It looks OK for now and separate the build options when enabling COLO shared 
disk mode.

Thanks
Chen

> 
> 
> --
> Best regards,
> Vladimir