[sheepdog] [sheepdog/sheepdog] e98977: sheep: avoid diskfull caused by recovery process

AP sheepdog at inml.weebeastie.net
Mon May 16 15:50:03 CEST 2016

On Mon, May 02, 2016 at 06:04:53PM +0900, Hitoshi Mitake wrote:
> On Sun, May 1, 2016 at 12:14 PM, AP <sheepdog at inml.weebeastie.net> wrote:
> > On Tue, Apr 26, 2016 at 07:20:15PM -0700, Hitoshi Mitake wrote:
> > > sheep can corrupt its cluster by diskfull with recovery process. For
> > > avoiding this problem, this patch adds a new option -F to dog cluster
> > > format. If this command is passed during cluster formatting, every
> > > sheep process of the cluster skips recovery if there is a possibility
> > > of diskfull during recovery.
> >
> > I'm a little confused and am wondering if I am reading this incoorectly.
> >
> > This sounds like the default is to set up the cluster in such a way that
> > it'll corrupt itself.
> >
> > Shouldn't it be the other way around? That the default should leave you
> > safe and you have the option of running naked through the poison ivy
> > if that's your idea of fun.
> >
> > Or did I miss something?
> The default setup will corrupt the cluster if there is no enough space for
> recovery as you say. However, the new option can result a situation that
> some objects lack its enough replicas. Maybe adding a new option for
> killing the cluster itself when there's no enough space would be good.

Sorry for not replying earlier. Life is a mix of sleep, work and sleep,
atm. :/

Unfortunately I don't understand the above. Specifically "can result
a situation that some objects lack its enough replicas". Lack what
exactly? :)

It sounds like the default is to permit overcommit which can result in
corruption when the space is not there at a critical time. If this is
the case then this should be a conscious decision made by the admin and
the default is to go "Your data is precious - have enough space for what
you want." It'd be the option of least surprise.

If I'm barking up the wrong tree (possible - I'm not sure what you
meant in your reply) then my apologies. Would love a clarificaiton,
time permitting.

Hopefully I'm not too late in replying.


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