Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: hdfs-issues@hadoop.apache.org
Message-ID: <31044052.525881282635496702.JavaMail.jira@thor>
Date: Tue, 24 Aug 2010 03:38:16 -0400 (EDT)
From: "dhruba borthakur (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Subject: [jira] Commented: (HDFS-1351) Make it possible for
 BlockPlacementPolicy to return null
In-Reply-To: <4239133.525791282634716856.JavaMail.jira@thor>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/HDFS-1351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12901758#action_12901758 ] 

dhruba borthakur commented on HDFS-1351:
----------------------------------------

In particular, the following interface in BlockPlacementPolicy.java could return null:

{code}

  abstract public DatanodeDescriptor chooseReplicaToDelete(FSInodeInfo srcInode,
                                      Block block,
                                      short replicationFactor,
                                      Collection<DatanodeDescriptor> existingReplicas,
                                      Collection<DatanodeDescriptor> moreExistingReplicas);
{code}

> Make it possible for BlockPlacementPolicy to return null
> --------------------------------------------------------
>
>                 Key: HDFS-1351
>                 URL: https://issues.apache.org/jira/browse/HDFS-1351
>             Project: Hadoop HDFS
>          Issue Type: Test
>          Components: name-node
>    Affects Versions: 0.22.0
>            Reporter: Dmytro Molkov
>            Assignee: Dmytro Molkov
>
> The idea is to modify FSNamesystem.chooseExcessReplicates code, so it can accept a null return from chooseReplicaToDelete which will indicate that NameNode should not be deleting extra replicas.
> One possible usecase - if there are nodes being added to the cluster that might have corrupt replicas on them you do not want to delete other replicas until the block scanner finished scanning every block on the datanode.
> This will require additional work on the implementation of the BlockPlacementPolicy, but with this JIRA I just wanted to create a basis for future improvements.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.