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From Jun Rao <jun...@gmail.com>
Subject Re: slow log recovery
Date Tue, 07 May 2013 14:55:14 GMT
If a broker is down, the cluster will be running in under replicated mode,
ie, data will be written to fewer replicas. When the broker comes back, it
will catch up data from the current leader.

Thanks,

Jun


On Mon, May 6, 2013 at 10:23 PM, Jason Rosenberg <jbr@squareup.com> wrote:

> Will producers also be able to start sending new messages to a replica,
> while one broker is taking a long time to startup?
>
>
> On Mon, May 6, 2013 at 9:31 PM, Jun Rao <junrao@gmail.com> wrote:
>
> > In 0.8, if you turn on replication, it may not matter too much if a
> broker
> > takes long to start up since data can still be served from the replicas.
> It
> > may be possible to improve this by maintaining a flush checkpoint file on
> > disk. We can then use that info to reduce the amount of the data to be
> > recovered.
> >
> > Thanks,
> >
> > Jun
> >
> >
> > On Mon, May 6, 2013 at 3:07 PM, Jason Rosenberg <jbr@squareup.com>
> wrote:
> >
> > > Recently, we had an issue where our kafka brokers were shut down hard
> > (and
> > > so did not write out the clean shutdown file).  Thus on restart, it
> went
> > > through all logs and ran a recovery on them.
> > >
> > > Unfortunately, this took a long time (on the order of 30 minutes).  We
> > have
> > > a lot of topics (e.g. ~1000 or so).  Is there anyway this can be done
> > more
> > > quickly, say in parallel?
> > >
> > > Also, it be done as a background process, so the server can start up
> and
> > > start receiving messages, logs for incoming topics are prioritized in
> the
> > > recovery process, and perhaps messages can still be buffered in memory
> > > while the log recovery is happening?
> > >
> > > It seems onerous to block all activity for 30 minutes while a slow,
> > serial,
> > > recovery job happens....
> > >
> > > Thoughts?
> > >
> > > Jason
> > >
> >
>

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