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Date: Wed, 29 Apr 2015 10:29:44 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH COLO v3 01/14] docs: block replication's
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Yang Hongyang <yanghy@cn.fujitsu.com>, Fam Zheng <famz@redhat.com>, qemu block <qemu-block@nongnu.org>, armbru@redhat.com, jcody@redhat.com, Jiang Yunhong <yunhong.jiang@intel.com>, Dong Eddie <eddie.dong@intel.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, qemu devel <qemu-devel@nongnu.org>, zhanghailiang <zhang.zhanghailiang@huawei.com>, Gonglei <arei.gonglei@huawei.com>, Max Reitz <mreitz@redhat.com>, Lai Jiangshan <laijs@cn.fujitsu.com>



On 27/04/2015 11:37, Stefan Hajnoczi wrote:
>>> But it's only for the failover case.  Quorum (or a new 
>>> block/colo.c driver or filter) is fine for normal colo 
>>> operation.
> Perhaps this patch series should mirror the Secondary's disk to a 
> Backup Secondary so that the system can be protected very quickly 
> after failover.
> 
> I think anyone serious about fault tolerance would deploy a Backup
>  Secondary, otherwise the system cannot survive two failures
> unless a human administrator is lucky/fast enough to set up a new 
> Secondary.

Let's do one thing at a time.  Otherwise nothing of this is going to
be ever completed...

Paolo