[
https://issues.apache.org/jira/browse/HDFS-512?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12739212#action_12739212
]
Hairong Kuang commented on HDFS-512:
------------------------------------
> Why does ReplicaInfo need genStamp field. Don't we always have it in Block?
> If we do could you please add a comment clarifying what this field actually
> is.
Now the key is block id so the returned entry from the map may have a different
generation stamp but there is no efficient way to get the key in the map so I
add the generation stamp to the value field.
> Set block id as the key to Block
> --------------------------------
>
> Key: HDFS-512
> URL: https://issues.apache.org/jira/browse/HDFS-512
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 0.21.0
> Reporter: Hairong Kuang
> Assignee: Hairong Kuang
> Fix For: 0.21.0
>
> Attachments: blockKey.patch
>
>
> Currently the key to Block is block id + generation stamp. I would propose to
> change it to be only block id. This is based on the following properties of
> the dfs cluster:
> 1. On each datanode only one replica of block exists. Therefore there is only
> one generation of a block.
> 2. NameNode has only one entry for a block in its blocks map.
> With this change, search for a block/replica's meta information is easier
> since most of the time we know a block's id but may not know its generation
> stamp.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
