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Posted to common-dev@hadoop.apache.org by "Raghu Angadi (JIRA)" <ji...@apache.org> on 2009/01/05 20:23:44 UTC

[jira] Commented: (HADOOP-3988) The elephant should remember names, not numbers.

    [ https://issues.apache.org/jira/browse/HADOOP-3988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12660865#action_12660865 ] 

Raghu Angadi commented on HADOOP-3988:
--------------------------------------

Thanks Steve. Based on the above comments, we need to do couple of things :

- If a configuration variable for ttl is not default, DN (and may be clients) set an explicit ttl (through "networkaddress.cache.ttl").
- RPC clients re-resolve RPC servers for a new connection, if the last resolution was at least "ttl" ego.

So that admin could set the ttl to 10 minutes and RPC clients resolve at at most once every 10 minutes.

> The elephant should remember names, not numbers.
> ------------------------------------------------
>
>                 Key: HADOOP-3988
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3988
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.17.2
>            Reporter: Allen Wittenauer
>
> The name node and the data node should not cache the resolution of host names, as doing so prevents the use of DNS CNAMEs for any sort of fail over capability.

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