Hi Ray,
You'll probably find that even though the name node starts, it doesn't
have any data nodes and is completely empty.
Whenever hadoop creates a new filesystem, it assigns a large random
number to it to prevent you from mixing datanodes from different
filesystems on accident. When you reformat the name node its FS has one
ID, but your data nodes still have chunks of the old FS with a different
ID and so will refuse to connect to the namenode. You need to make sure
these are cleaned up before reformatting. You can do it just by deleting
the data node directory, although there's probably a more "official" way
to do it.
On 11/10/09 11:01 AM, Raymond Jennings III wrote:
On the actual datanodes I see the following exception: I am not sure what the
namespaceID is or how to sync them. Thanks for any advice!
/************************************************************
STARTUP_MSG: Starting DataNode
STARTUP_MSG: host = pingo-3.poly.edu/128.238.55.33
STARTUP_MSG: args = []
STARTUP_MSG: version = 0.20.1
STARTUP_MSG: build =
http://svn.apache.org/repos/asf/hadoop/common/tags/release-0.20.1-rc1 -r
810220; compiled by 'oom' on Tue Sep 1 20:55:56 UTC 2009
************************************************************/
2009-11-09 09:57:45,328 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode:
java.io.IOException: Incompatible namespaceIDs in /tmp/hadoop-root/dfs/data:
namenode namespaceID = 1016244663; datanode namespaceID = 1687029285
at
org.apache.hadoop.hdfs.server.datanode.DataStorage.doTransition(DataStorage.java:233)
at
org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:148)
at
org.apache.hadoop.hdfs.server.datanode.DataNode.startDataNode(DataNode.java:298)
at
org.apache.hadoop.hdfs.server.datanode.DataNode.<init>(DataNode.java:216)
at
org.apache.hadoop.hdfs.server.datanode.DataNode.makeInstance(DataNode.java:1283)
at
org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:1238)
at
org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:1246)
at
org.apache.hadoop.hdfs.server.datanode.DataNode.main(DataNode.java:1368)
--- On Mon, 11/9/09, Boris Shkolnik<[email protected]> wrote:
From: Boris Shkolnik<[email protected]>
Subject: Re: newbie question - error with replication
To: [email protected]
Date: Monday, November 9, 2009, 5:02 PM
Make sure you have at least one
datanode running.
Look at the data node log file. (logs/*-datanode-*.log)
Boris.
On 11/9/09 7:15 AM, "Raymond Jennings III"<[email protected]>
wrote:
I am trying to resolve an IOException error. I
have a basic setup and shortly
after running start-dfs.sh I get a:
error: java.io.IOException: File
/tmp/hadoop-root/mapred/system/jobtracker.info could
only be replicated to 0
nodes, instead of 1
java.io.IOException: File
/tmp/hadoop-root/mapred/system/jobtracker.info could
only be replicated to 0 nodes, instead of 1
Any pointers how to resolve this? Thanks!
