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Re: Datanode error
Could also be due to network issues. Number of sockets could be less or number of threads could be less.

Raj

>________________________________
> From: Harsh J <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Sent: Friday, July 20, 2012 9:06 AM
>Subject: Re: Datanode error
>
>Pablo,
>
>These all seem to be timeouts from clients when they wish to read a
>block and drops from clients when they try to write a block. I
>wouldn't think of them as critical errors. Aside of being worried that
>a DN is logging these, are you noticing any usability issue in your
>cluster? If not, I'd simply blame this on stuff like speculative
>tasks, region servers, general HDFS client misbehavior, etc.
>
>Please do also share if you're seeing an issue that you think is
>related to these log messages.
>
>On Fri, Jul 20, 2012 at 6:37 PM, Pablo Musa <[EMAIL PROTECTED]> wrote:
>> Hey guys,
>> I have a cluster with 11 nodes (1 NN and 10 DNs) which is running and working.
>> However my datanodes keep having the same errors, over and over.
>>
>> I googled the problems and tried different flags (ex: -XX:MaxDirectMemorySize=2G)
>> and different configs (xceivers=8192) but could not solve it.
>>
>> Does anyone know what is the problem and how can I solve it? (the stacktrace is at the end)
>>
>> I am running:
>> Java 1.7
>> Hadoop 0.20.2
>> Hbase 0.90.6
>> Zoo 3.3.5
>>
>> % top -> shows low load average (6% most of the time up to 60%), already considering the number of cpus
>> % vmstat -> shows no swap at all
>> % sar -> shows 75% idle cpu in the worst case
>>
>> Hope you guys can help me.
>> Thanks in advance,
>> Pablo
>>
>> 2012-07-20 00:03:44,455 INFO org.apache.hadoop.hdfs.server.datanode.DataNode.clienttrace: src: /DN01:50010, dest:
>> /DN01:43516, bytes: 396288, op: HDFS_READ, cliID: DFSClient_hb_rs_DN01,60020,1342734302945_1342734303427, offset: 54956544, srvID: DS-798921853-DN01-50010-1328651609047, blockid: blk_914960691839012728_14061688, duration:
>> 480061254006
>> 2012-07-20 00:03:44,455 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(DN01:50010, storageID=DS-798921853-DN01-50010-1328651609047, infoPort=50075, ipcPort=50020):Got exception while serving blk_914960691839012728_14061688 to /DN01:
>> java.net.SocketTimeoutException: 480000 millis timeout while waiting for channel to be ready for write. ch : java.nio.channels.SocketChannel[connected local=/DN01:50010 remote=/DN01:43516]
>>         at org.apache.hadoop.net.SocketIOWithTimeout.waitForIO(SocketIOWithTimeout.java:246)
>>         at org.apache.hadoop.net.SocketOutputStream.waitForWritable(SocketOutputStream.java:159)
>>         at org.apache.hadoop.net.SocketOutputStream.transferToFully(SocketOutputStream.java:198)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendChunks(BlockSender.java:397)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendBlock(BlockSender.java:493)
>>         at org.apache.hadoop.hdfs.server.datanode.DataXceiver.readBlock(DataXceiver.java:279)
>>         at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:175)
>>
>> 2012-07-20 00:03:44,455 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(DN01:50010, storageID=DS-798921853-DN01-50010-1328651609047, infoPort=50075, ipcPort=50020):DataXceiver
>> java.net.SocketTimeoutException: 480000 millis timeout while waiting for channel to be ready for write. ch : java.nio.channels.SocketChannel[connected local=/DN01:50010 remote=/DN01:43516]
>>         at org.apache.hadoop.net.SocketIOWithTimeout.waitForIO(SocketIOWithTimeout.java:246)
>>         at org.apache.hadoop.net.SocketOutputStream.waitForWritable(SocketOutputStream.java:159)
>>         at org.apache.hadoop.net.SocketOutputStream.transferToFully(SocketOutputStream.java:198)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendChunks(BlockSender.java:397)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendBlock(BlockSender.java:493)
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB