[jira] [Commented] (HDFS-4184) Add the ability for Client to provide more hint information for DataNode to manage the OS buffer cache more accurate

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

    [ https://issues.apache.org/jira/browse/HDFS-4184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13495911#comment-13495911 ] 

stack commented on HDFS-4184:
-----------------------------

[~aoxiang] Want to reopen this issue now you've filled in detail?
                
> Add the ability for Client to provide more hint information for DataNode to manage the OS buffer cache more accurate
> --------------------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-4184
>                 URL: https://issues.apache.org/jira/browse/HDFS-4184
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>            Reporter: binlijin
>
> HDFS now has the ability to use posix_fadvise and sync_data_range syscalls to manage the OS buffer cache.
> {code}
> When hbase read hlog the data we can set dfs.datanode.drop.cache.behind.reads to true to drop data out of the buffer cache when performing sequential reads.
> When hbase write hlog we can set dfs.datanode.drop.cache.behind.writes to true to drop data out of the buffer cache after writing
> When hbase read hfile during compaction we can set dfs.datanode.readahead.bytes to a non-zero value to trigger readahead for sequential reads.
> and so on... 
> {code}

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira