[sheepdog] [PATCH v2 1/4] sheep: leave cluster after unpluging all disks

[Robin Dong]

2014-06-20 16:51 GMT+08:00 Liu Yuan <namei.unix at gmail.com>:

> On Fri, Jun 20, 2014 at 04:21:27PM +0800, Robin Dong wrote:
> > From: Robin Dong <sanbai at taobao.com>
> >
> > After following steps:
> >
> >  1. start 6 sheep cluster, every sheep has 4 data path
> >  2. unplug 4 data path for one sheep daemon
> >
> > then we will see the sheep daemon which has no data path is also
> > in the cluster by using 'dog node list'.But a sheep daemon with
> > no data path should be a pure gateway.
> >
> > So we should return EIO after unpluging last disk which will cause
> > sheep to leave cluster.
> >
>
> sheep will leave cluster by EIO later when it tries to access disks. See
> md_handle_eio().
>

> Suppose you unplug all the 4 disks for maintainance and then plug back 4
> new
> disks. We should allow this use case, so this patch looks wrong to me.


> By the way, what is purpose of making a sheep as pure gateway while
> running?
>

If all disks corrupt, the sheep daemon on this node will become a pure
gateway, after this,
some one 's wrong operation (such as plug a new disk) will make all nodes
coredump.


>
> Thanks
> Yuan
>



-- 
--
Best Regard
Robin Dong
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