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From David Koch <ogd...@googlemail.com>
Subject Re: : Region Servers crashing following: "File does not exist", "Too many open files" exceptions
Date Sun, 10 Feb 2013 02:17:26 GMT

Thank you for your reply, I checked the HDFS log for error messages that
are indicative of "xciever" problems but could not find any. The settings
suggested here:
http://blog.cloudera.com/blog/2012/03/hbase-hadoop-xceivers/have been
applied on our cluster.

I did a grep "File does not exist: /hbase/<table_name>/"
/var/log/hadoop-hdfs/hadoop-cmf-hdfs1-NAMENODE-big* | wc

on the namenode logs and there millions of such lines for one table only.
The count is 0 for all other tables - even though they may be reported as
inconsistent by hbchk.

It seems like this is less of a performance issue but rather some stale
"where to find what data" problem - possibly related to Zookeeper? I
remember there being some kind of procedure for clearing ZK even though I
cannot recall the steps involved.

Any further help would be appreciated,



On Sun, Feb 10, 2013 at 2:24 AM, Dhaval Shah <prince_mithibai@yahoo.co.in>wrote:

> It seems like you need to increase the limit on the number of xceivers on
> the hdfs config looking at your error messages.
> ------------------------------
> On Sun 10 Feb, 2013 6:37 AM IST David Koch wrote:
> >Hello,
> >
> >As of lately, we have been having issues with Region Servers crashing in
> >our cluster. This happens while running Map/Reduce jobs over HBase tables
> >in particular but also spontaneously when the cluster is seemingly idle.
> >
> >Restarting the Region Servers or even HBase entirely as well as HDFS and
> >Map/Reduce services does not fix the problem and jobs will fail during the
> >next attempt citing "Region not served" exceptions. It is not always the
> >same nodes that crash.
> >
> >The log data during the minutes leading up to the crash contain many "File
> >does not exist /hbase/<table_name>/..." error messages which change to
> "Too
> >many open files" messages, finally, there are a few "Failed to renew lease
> >for DFSClient" messages followed by several "FATAL" messages about HLog
> not
> >being able to synch and immediately afterwards a terminal "ABORTING region
> >server".
> >
> >You can find an extract of a Region Server log here:
> >http://pastebin.com/G39LQyQT.
> >
> >Running "hbase hbck" reveals inconsistencies in some tables, but
> attempting
> >a repair with "hbase hbck -repair" stalls due to some regions being in
> >transition, see here: http://pastebin.com/JAbcQ4cc.
> >
> >The setup contains 30 machines, 26GB RAM each, the services are managed
> >using CDH4, so HBase version is 0.92.x. We did not tweak any of the
> default
> >configuration settings, however table scans are done with sensible
> >scan/batch/filter settings.
> >
> >Data intake is about 100GB/day which are added at a time when no
> Map/Reduce
> >jobs are running. Tables have between 100 * 10^6 and 2 * 10^9 rows, with
> an
> >average of 10 KVs, about 1kb each. Very few rows exceed 10^6 KV.
> >
> >What can we do to fix these issues? Are they symptomic of a mal-configured
> >setup or some critical threshold level being reached? The cluster used to
> >be stable.
> >
> >Thank you,
> >
> >/David

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