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From Andrew Purtell <apurt...@apache.org>
Subject Re: Region servers going down frequently (0.20 alpha)
Date Mon, 29 Jun 2009 06:44:57 GMT

Configuring 'myid' files are part of the Zookeeper set up process.
Are you aware of the instructions for how to set up Zookeeper here: 





"For reliable ZooKeeper service, you should deploy ZooKeeper in a cluster known as an ensemble.
[...] Here are the steps to setting a server that will be part of an ensemble. These steps
should be performed on every host in the ensemble: ..."

   - Andy

From: Murali Krishna. P <muralikpbhat@yahoo.com>
To: hbase-user@hadoop.apache.org
Sent: Sunday, June 28, 2009 10:12:02 PM
Subject: Re: Region servers going down frequently (0.20 alpha)

Hi Andrew,
Thanks for looking into this.
I tried adding 3 nodes to the zoo.cfg but it threw an erros saying 'myid' file is missing.
Now even if i go back to my old config, it still throws the error :(

Murali Krishna

From: Andrew Purtell <apurtell@apache.org>
To: hbase-user@hadoop.apache.org
Sent: Sunday, 28 June, 2009 10:47:12 PM
Subject: Re: Region servers going down frequently (0.20 alpha)


As a first step, deploy Zookeeper quorum peers on all of your nodes and 
list all peers in the zoo.cfg files of your Zookeeper install and HBase:


Are you running mapreduce tasks as well as otherwise what you have described

Do you see any messages in the master or region server logs along the lines
of "we slept for NNNNNNms, wanted NNNNms"? How much RAM do these nodes have?
Do you have host level metrics running? If not, consider watching this with
Ganglia, or, in this case, since the cluster is so small three terminals
running top or atop. After 20, 30 minutes, is all available RAM full and are
the nodes going in to swap? 

   - Andy

From: Murali Krishna. P <muralikpbhat@yahoo.com>
To: hbase-user@hadoop.apache.org
Sent: Sunday, June 28, 2009 8:23:27 AM
Subject: Region servers going down frequently (0.20 alpha)

  I am repeatedly running into this issue where all the region servers tries to restart but
fails to come up. All the region servers seems to be having same kind of exception which causes
this state.

My cluster is as follows:
node1 : Master, NN, DN, RS, TT, XX
node2: Zookeeper, JT, DN, RS, TT, XX
node3: DN, RS, TT, XX

where  XX is my own hbase client with around 150 threads writing to a common table.

The setup works fine for some time and then goes down (after 20, 30 mins). Here is the sequence
in the region server logs..

    * RS gets a zookeeper event : Got ZooKeeper event, state: Disconnected, type: None, path:

    * RS retries 'processing image', gets LeaseStillHeldE: 2009-06-28 02:14:17,013 WARN org.apache.hadoop.hbase.regionserver.HRegionServer:
Processing message (Retry: 1)
    * After 10 retries, gets another zoookeeper event : Got ZooKeeper event, state: Expired,
type: None, path: null
2009-06-28 02:14:17,751 ERROR org..apache.hadoop.hbase.regionserver.HRegionServer: ZooKeeper
session expired
2009-06-28 02:14:17,751 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Restarting
Region Server
    * Decides to restart region server, but logs of error like this: 2009-06-28 02:14:17,997
INFO org.apache.hadoop.ipc.HBaseServer: IPC Server handler 280 on 60020, call exists([B@75880048,
row=724b330295375ad0ba68fa85325381, maxVersions=1, timeRange=[0,9223372036854775807), families=ALL)
from error: java.io.IOException: Ser
ver not running, aborting
    * Above might be happening because client 'XX' still trying to write? Finally it closes
the region server and tries to restart. But gets the following exception:2009-06-28 02:14:26,462
INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Starting shutdown thread.
2009-06-28 02:14:26,462 INFO org.apache.hadoop.hbase..regionserver.HRegionServer: Runs every
2009-06-28 02:14:26,462 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Shutdown
thread complete
2009-06-28 02:14:27,032 ERROR org.apache.hadoop.hbase.regionserver.HRegionServer: Failed init
        at org.apache.hadoop.hbase.regionserver.HRegionServer.init(HRegionServer.java:713)
        at org.apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer..java:431)
        at java.lang.Thread.run(Thread.java:619)
2009-06-28 02:14:27,110 FATAL org.apache.hadoop.hbase.regionserver.HRegionServer: Unhandled
exception. Aborting...
java.io.IOException: Region server startup failed
        at org.apache.hadoop.hbase.regionserver.HRegionServer.convertThrowableToIOE(HRegionServer.java:832)
        at org.apache.hadoop.hbase.regionserver.HRegionServer.init(HRegionServer.java:751)
        at org..apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer.java:431)
        at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
        at org.apache.hadoop.hbase.regionserver.HRegionServer.init(HRegionServer.java:713)
        ... 2 more
2009-06-28 02:14:27,122 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Dump of metrics:
request=0.0, regions=9, stores=10, storefil
es=20, storefileIndexSize=0, memcacheSize=52, usedHeap=170, maxHeap=1995, blockCacheSize=49971560,
blockCacheFree=28440, blockCacheCount=765,
2009-06-28 02:14:27,131 INFO org.apache.hadoop.ipc.HBaseServer: Stopping server on 60020
2009-06-28 02:14:27,131 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Stopping
2009-06-28 02:14:27,131 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: On abort,
closed hlog
2009-06-28 02:14:27,136 INFO org.apache.hadoop.hbase..regionserver.HRegionServer: aborting
server at:

There region server dies after that. All the 3 region servers die like this and I have to
start the region server manually. But aftert 10-15 minutes, it runs into the same stage again.
Please help me in finding what is the root cause of this?

Murali Krishna

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