[jira] Commented: (HADOOP-988) Namenode should use single map for block to its meta data.

["Raghu Angadi (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12482456 ] 

Raghu Angadi commented on HADOOP-988:
-------------------------------------


removed 2.patch. Not necessary right now. I will include a different patch that fixes 'dfsadmin -report' also later.

> Namenode should use single map for block to its meta data.
> ----------------------------------------------------------
>
>                 Key: HADOOP-988
>                 URL: https://issues.apache.org/jira/browse/HADOOP-988
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: dfs
>            Reporter: Raghu Angadi
>         Assigned To: Raghu Angadi
>         Attachments: HADOOP-988-1.patch
>
>
> This is a follow up from HADOOP-803. Currently there two maps which have similar functionality :
>    1) blockMap : maps block to list of datanodes  that contain the block
>    2) activeBlocks : maps block to INode that it blongs to.
> Apart from simplifying, it saves 32 bytes per block and 24 bytes by avoid extra block object we currently have for files that exist before Namenode starts (see HADOOP-803).
> We could combine these two into something like block to { containingNodes, INode, etc }. 
> Another option is to get Move INode and list of dataNodes into Block object.
> Another option that requires bigger change is not use Block object but just 64 bit BlockId. Then the map would be BlockId to all the block related info. I will file another Jira regd not using Block object in NameNode.

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