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https://issues.apache.org/jira/browse/HDFS-6919?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14490336#comment-14490336
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Arpit Agarwal commented on HDFS-6919:
-------------------------------------
As a first step the memory writer can reserve space for a full replica in
FsDatasetCache. The memory will be released if a block is finalized at less
than full length or when the block is evicted from ramfs. This gets us towards
a unified configuration for both features via
{{dfs.datanode.max.locked.memory}}. I looked at the FsDatasetCache code and the
change seems easy in theory.
Next we could add a hook for CCM to evict ramfs replicas.
> Enforce a single limit for RAM disk usage and replicas cached via locking
> -------------------------------------------------------------------------
>
> Key: HDFS-6919
> URL: https://issues.apache.org/jira/browse/HDFS-6919
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Arpit Agarwal
> Assignee: Arpit Agarwal
>
> The DataNode can have a single limit for memory usage which applies to both
> replicas cached via CCM and replicas on RAM disk.
> See comments
> [1|https://issues.apache.org/jira/browse/HDFS-6581?focusedCommentId=14106025&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14106025],
>
> [2|https://issues.apache.org/jira/browse/HDFS-6581?focusedCommentId=14106245&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14106245]
> and
> [3|https://issues.apache.org/jira/browse/HDFS-6581?focusedCommentId=14106575&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14106575]
> for discussion.
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