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From "Yoram Arnon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-514) namenode heartbeat interval should be configurable
Date Fri, 08 Sep 2006 20:56:24 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-514?page=comments#action_12433496 ] 
Yoram Arnon commented on HADOOP-514:

agreed, the dfs needs to be responsive.
but the larger the system, the more frequently datanodes hit the name node.
a block that awaits re-replication will get replicated to the first node that sends a heartbeat
and makes sense as a replication destination. Overall the system is very responsive even though
each individual data node sends infrequent heartbeats.
as for deletions, they can wait a bit, especially with undelete functionality in mind.
The formula max(nodes/10, 1) maintains heartbeat rate at a constant 10 per second at the namenode.
We can tweak the denominator to change that rate, but this seems like a good rate to get responsiveness,
while limiting the load on the namenode.

> namenode heartbeat interval should be configurable
> --------------------------------------------------
>                 Key: HADOOP-514
>                 URL: http://issues.apache.org/jira/browse/HADOOP-514
>             Project: Hadoop
>          Issue Type: Bug
>          Components: dfs
>            Reporter: Wendy Chien
> The namenode heartbeat interval is currently a constant in FSConstants.   It should be
configurable instead.  Things which currently rely on the heartbeat occuring fairly frequently
should be disassociated.    

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