Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Zookeeper >> mail # user >> Failure to rejoin ensemble after reboot


Copy link to this message
-
Re: Failure to rejoin ensemble after reboot
I was thinking the same thing when I answered that email earlier this week
about the lack of myid causing an error that is difficult to trace. I kind
of hate the myid file, why is it necessary in the first place? There must
be a cleaner way for us to identify servers and avoid conflicts.

C

On Mon, Jul 9, 2012 at 10:14 AM, Marshall McMullen <
[EMAIL PROTECTED]> wrote:

> As it turns out, it was a configuration problem. We use zookeeper in an
> embedded manner so our application code creates the myid file
> programatically when we start zookeeper. After the reboot, it was creating
> the 'myid' file and putting the wrong value in there. This was a value of
> another ensemble node already in the cluster. I can't believe how much time
> was wasted on such a simple configuration problem. Given how fatal this
> was, it might have been useful if ZK could have detected multiple servers
> with the same ID and given a more helpful error message. But in any event,
> problem is solved now.... thanks for taking the time to respond Camille.
>
> On Mon, Jul 9, 2012 at 8:09 AM, Camille Fournier <[EMAIL PROTECTED]>
> wrote:
>
> > That is very strange. What do the logs of the misbehaving server say?
> What
> > do the logs of the other servers say? What does a stack dump of the
> > misbehaving server look like?
> > Also, just to clarify, if you don't do anything but fully stop and
> restart
> > the cluster (no deleting version-2 files etc) the whole ensemble will
> > reform successfully?
> >
> > C
> >
> > On Mon, Jul 9, 2012 at 12:44 AM, Marshall McMullen <
> > [EMAIL PROTECTED]> wrote:
> >
> > > I'm trying to get to the bottom of a problem we're seeing where after I
> > > forcibly reboot an ensemble node (running on Linux) via "reboot -f" it
> is
> > > unable to rejoin the ensemble and no clients can connect to it. Has
> > anyone
> > > ever seen a problem like this before?
> > >
> > > I have been investigating this under
> > > https://issues.apache.org/jira/browse/ZOOKEEPER-1453 as on the surface
> > it
> > > looked like there was some sort of transaction/log corruption going on.
> > But
> > > now I'm not so sure of that.
> > >
> > > What bothers me the most right now is that I am unable to reliably get
> > the
> > > node in question to rejoin the ensemble. I've removed the contents of
> the
> > > "version-2" directory and restarted zookeeper to no avail. It
> regenerates
> > > an epoch file but never obtains the new database from a peer. I event
> > went
> > > so far as to copy the on-disk database from another node and restart
> > > zookeeper and I still can't get it to rejoin the ensemble. I've also
> > > seen anomalous behavior where once I get it into this failed state, I
> > just
> > > stopped all three zookeeper server processes entirely then start them
> all
> > > back up... then everything connects and all three nodes are in the
> > > ensemble. But this really shouldn't be necessary.
> > >
> > > None of this matches the behavior I expected. Anyone have any insight
> it
> > > would be greatly appreciated.
> > >
> >
>