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From: Wen Congyang <wency@cn.fujitsu.com>
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Date: Thu, 21 Jan 2016 09:54:10 +0800
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Subject: Re: [Qemu-devel] [PATCH v9 2/3] quorum: implement bdrv_add_child()
 and bdrv_del_child()
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To: Alberto Garcia <berto@igalia.com>, Changlong Xie <xiecl.fnst@cn.fujitsu.com>, qemu devel <qemu-devel@nongnu.org>, Eric Blake <eblake@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>
Cc: zhanghailiang <zhang.zhanghailiang@huawei.com>, qemu block <qemu-block@nongnu.org>, Jiang Yunhong <yunhong.jiang@intel.com>, Dong Eddie <eddie.dong@intel.com>, Markus Armbruster <armbru@redhat.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Gonglei <arei.gonglei@huawei.com>

On 01/20/2016 11:43 PM, Alberto Garcia wrote:
> On Fri 25 Dec 2015 10:22:55 AM CET, Changlong Xie wrote:
>> @@ -875,9 +878,9 @@ static int quorum_open(BlockDriverState *bs, QDict *options, int flags,
>>          ret = -EINVAL;
>>          goto exit;
>>      }
>> -    if (s->num_children < 2) {
>> +    if (s->num_children < 1) {
>>          error_setg(&local_err,
>> -                   "Number of provided children must be greater than 1");
>> +                   "Number of provided children must be 1 or more");
>>          ret = -EINVAL;
>>          goto exit;
>>      }
> 
> I have a question: if you have a Quorum with just one member and you add
> a new one, how do you know if it has the same data as the existing one?
> 
> In general, what do you do to make sure that the data in a new Quorum
> child is consistent with that of the rest of the array?

Quorum can have more than one child when it starts. But we don't do the
similar check. So I don't think we should do such check here.

Thanks
Wen Congyang

> 
> Berto
> 
> 
> .
>