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Zookeeper >> mail # user >> Failure to rejoin ensemble after reboot


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Marshall McMullen 2012-07-09, 04:44
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Camille Fournier 2012-07-09, 14:09
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Re: Failure to rejoin ensemble after reboot
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.
> >
>
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Camille Fournier 2012-07-09, 14:16
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Patrick Hunt 2012-07-09, 16:48
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Marshall McMullen 2012-07-09, 14:19