[
https://issues.apache.org/jira/browse/HADOOP-3426?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12626989#action_12626989
]
Raghu Angadi commented on HADOOP-3426:
--------------------------------------
> OK. One thing we can't rely on here is any kind of rDNS to work, hostname
> lookup may time out, etc.
Right. we need to discourage depending on rDNS unless it is really required.
rDNS failure should generally be not a fatal error.
> I was thinking a little private xen/vmware virtual cluster with no external
> connectivity or DNS. Its a self-contained network.
In that case using the first available ip address works, right?
> One thing that is hard when handling different network setups is actually
> [...]
agreed.. we should clarify the requirements, tolerate less perfect set ups, and
generally be more end user friendly :) .
> 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: 0.19.0
> Environment: Ubuntu 8.04, at home, no reverse DNS
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Minor
> Attachments: hadoop-3426.patch, hadoop-3426.patch
>
>
> 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.
