[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's descrip
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description |
Date: |
Thu, 23 Apr 2015 13:05:33 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Paolo Bonzini (address@hidden) wrote:
>
>
> On 23/04/2015 13:36, Kevin Wolf wrote:
> > Crap. Then we need to figure out dynamic reconfiguration for filters
> > (CCed Markus and Jeff).
> >
> > And this is really part of the fundamental operation mode and not just a
> > way to give users a way to change their mind at runtime? Because if it
> > were, we could go forward without that for the start and add dynamic
> > reconfiguration in a second step.
>
> I honestly don't know. Wen, David?
As presented at the moment, I don't see there's any dynamic reconfiguration
on the primary side at the moment - it starts up in the configuration with
the quorum(disk, NBD), and that's the way it stays throughout the fault-tolerant
setup; the primary doesn't start running until the secondary is connected.
Similarly the secondary startups in the configuration and stays that way;
the interesting question to me is what happens after a failure.
If the secondary fails, then your primary is still quorum(disk, NBD) but
the NBD side is dead - so I don't think you need to do anything there
immediately.
If the primary fails, and the secondary takes over, then a lot of the
stuff on the secondary now becomes redundent; does that stay the same
and just operate in some form of passthrough - or does it need to
change configuration?
The hard part to me is how to bring it back into fault-tolerance now;
after a primary failure, the secondary now needs to morph into something
like a primary, and somehow you need to bring up a new secondary
and get that new secondary an image of the primaries current disk.
Dave
> Paolo
>
> > Anyway, even if we move it to a second step, it looks like we need to
> > design something rather soon now.
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- 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, 2015/04/23
- 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, 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, 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 <=
- 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, Fam Zheng, 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, 2015/04/24
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Wen Congyang, 2015/04/24
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Dr. David Alan Gilbert, 2015/04/24
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Paolo Bonzini, 2015/04/24
- Re: [Qemu-block] [PATCH COLO v3 01/14] docs: block replication's description, Wen Congyang, 2015/04/24