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From "Konstantin Shvachko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-297) When selecting node to put new block on, give priority to those with more free space/less blocks
Date Wed, 14 Jun 2006 03:01:30 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-297?page=comments#action_12416114 ] 

Konstantin Shvachko commented on HADOOP-297:
--------------------------------------------

This is an important problem.
But sorting for each block allocation seems too expensive, even if done n log n.
Should we just permanently store a TreeMap or a PriorityQueue
of nodes "prioritized" by their remaining space?
This would require updating the map when DFs change,
but will be less expensive for allocations.


> When selecting node to put new block on, give priority to those with more free space/less
blocks
> ------------------------------------------------------------------------------------------------
>
>          Key: HADOOP-297
>          URL: http://issues.apache.org/jira/browse/HADOOP-297
>      Project: Hadoop
>         Type: Improvement

>   Components: dfs
>     Versions: 0.3.2
>     Reporter: Johan Oskarson
>     Priority: Minor
>  Attachments: priorityshuffle_v1.patch
>
> As mentioned in previous bug report:
> We're running a smallish cluster with very different machines, some with only 60 gb harddrives
> This creates a problem when inserting files into the dfs, these machines run out of space
quickly while some have plenty of space free.
> So instead of just shuffling the nodes, I've created a quick patch that first sorts the
target nodes by (freespace / blocks).
> It then randomizes the position of the first third of the nodes (so we don't put all
the blocks in the file on the same machine)
> I'll let you guys figure out how to improve this.
> /Johan

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