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Posted to common-dev@hadoop.apache.org by "Doug Cutting (JIRA)" <ji...@apache.org> on 2006/03/23 01:14:31 UTC
[jira] Commented: (HADOOP-64) DataNode should be capable of
managing multiple volumes
[ http://issues.apache.org/jira/browse/HADOOP-64?page=comments#action_12371494 ]
Doug Cutting commented on HADOOP-64:
------------------------------------
I am not convinced, w/o benchmarks, that this is required. Multiple datanodes in the same JVM (as currently implemented) share a single TCP connection to the namenode. However each currently sends separate heartbeats to the namenode. Thus the primary impact of the proposed change would be that these heartbeats could be combined into a single RPC. The processing on the server would be the same, only spread over fewer RPC calls. So this change is primarily warranted if heartbeat RPC overhead dominates namenode performance. Even if that's proven to be the case, then we can achieve a similar effect much more simply by increasing the heartbeat interval.
> DataNode should be capable of managing multiple volumes
> -------------------------------------------------------
>
> Key: HADOOP-64
> URL: http://issues.apache.org/jira/browse/HADOOP-64
> Project: Hadoop
> Type: Improvement
> Components: dfs
> Versions: 0.2
> Reporter: Sameer Paranjpye
> Assignee: Konstantin Shvachko
> Priority: Minor
> Fix For: 0.2
>
> The dfs Datanode can only store data on a single filesystem volume. When a node runs its disks JBOD this means running a Datanode per disk on the machine. While the scheme works reasonably well on small clusters, on larger installations (several 100 nodes) it implies a very large number of Datanodes with associated management overhead in the Namenode.
> The Datanod should be enhanced to be able to handle multiple volumes on a single machine.
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