[jira] Commented: (HDFS-855) namenode can save images in parallel to all directories in fs.name.dir

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

    [ https://issues.apache.org/jira/browse/HDFS-855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12795375#action_12795375 ] 

Eli Collins commented on HDFS-855:
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Is loading/saving the fsimage and edits log IO bound? If so than we should consider compressing before storing.

> namenode can save images in parallel to all directories in fs.name.dir
> ----------------------------------------------------------------------
>
>                 Key: HDFS-855
>                 URL: https://issues.apache.org/jira/browse/HDFS-855
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: name-node
>            Reporter: dhruba borthakur
>
> The namenode restart times can be reduced if the namenode can save its image to multiple directories (specified in fs.name.dir) in parallel.
> The NN has a 6 GB fsimage and 1 MB edits file. The NN needed 10 minutes to load fsimage/edits into memory. It needs 7 minutes to read the 6 GB image. There are two directories in fs.name.dir.  it takes about 2 minute to save the image into first directory and another 2 minutes to save the image to the second directory. 

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