Datanode does not start up if the local machines DNS isnt working right and
dfs.datanode.dns.interface==default
---------------------------------------------------------------------------------------------------------------
Key: HADOOP-3426
URL: https://issues.apache.org/jira/browse/HADOOP-3426
Project: Hadoop Core
Issue Type: Bug
Components: dfs
Affects Versions: 0.16.3
Environment: Ubuntu 8.04, at home, no reverse DNS
Reporter: Steve Loughran
Priority: Minor
This is the third Java project I've been involved in that doesnt work on my
home network, due to implementation issues with
java.net.InetAddress.getLocalHost(), issues that only show up on an unamanged
network. Fortunately my home network exists to find these problems early.
In hadoop, if the local hostname doesnt resolve, the datanode does not start up:
Caused by: java.net.UnknownHostException: k2: k2
at java.net.InetAddress.getLocalHost(InetAddress.java:1353)
at org.apache.hadoop.net.DNS.getDefaultHost(DNS.java:185)
at org.apache.hadoop.dfs.DataNode.startDataNode(DataNode.java:184)
at org.apache.hadoop.dfs.DataNode.(DataNode.java:162)
at org.apache.hadoop.dfs.ExtDataNode.(ExtDataNode.java:55)
at
org.smartfrog.services.hadoop.components.datanode.DatanodeImpl.sfStart(DatanodeImpl.java:60)
While this is a valid option in a production (non-virtual) cluster, if you are
playing with VMWare/Xen private networks or on a home network, you can't rely
on DNS.
1. In these situations, its usually better to fall back to using "localhost" or
127.0.0.1 as a hostname if Java can't work it out for itself,
2. Its often good to cache this if used in lots of parts of the system,
otherwise the 30s timeouts can cause problems of their own.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
