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Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's descrip
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description |
Date: |
Thu, 23 Apr 2015 12:17:16 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 23.04.2015 um 12:05 hat Paolo Bonzini geschrieben:
>
>
> On 23/04/2015 11:14, Wen Congyang wrote:
> > The bs->file->driver should support backing file, and use backing reference
> > already.
> >
> > What about the primary side? We should control when to connect to NBD
> > server,
> > not in nbd_open().
Why do you need to create the block device before the connection should
be made?
> My naive suggestion could be to add a BDRV_O_NO_CONNECT option to
> bdrv_open and a separate bdrv_connect callback. Open would fail if
> BDRV_O_NO_CONNECT is specified and drv->bdrv_connect is NULL.
>
> You would then need a way to have quorum pass BDRV_O_NO_CONNECT.
Please don't add new flags. If we have to, we can introduce a new option
(in the QDict), but first let's check if it's really necessary.
> Perhaps quorum is not a great match after all, and it's better to add a
> new "colo" driver similar to quorum but simpler and only using the read
> policy that you need for colo. The new driver would also know how to
> use BDRV_O_NO_CONNECT. In any case the amount of work needed would not
> be too big.
I thought the same, but haven't looked at the details yet. But if I
understand correctly, the plan is to take quorum and add options to turn
off the functionality of using a quorum - that's a bit odd.
What I think is really needed here is essentially an active mirror
filter.
Kevin
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, (continued)
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Kevin Wolf, 2015/04/22
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/22
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Kevin Wolf, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Wen Congyang, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Kevin Wolf, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Wen Congyang, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description,
Kevin Wolf <=
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Kevin Wolf, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Wen Congyang, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Kevin Wolf, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Dr. David Alan Gilbert, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Dr. David Alan Gilbert, 2015/04/23
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/23