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https://issues.apache.org/jira/browse/HDFS-1435?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12916938#action_12916938
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Hairong Kuang commented on HDFS-1435:
-------------------------------------

Phillip, your suggestion definitely has value that gives the flexibility of 
compressing fsimage at any time. The focus of this jira is to store it 
compressed by HDFS. This allows secondary NN to transfer the compressed image 
to primary NN, thus reducing network & disk I/O overhead.

Jeff, I'd like to take a look at the Avro file format. Do you know if Avro file 
format has any overhead than the current fsimage format?

> Provide an option to store fsimage compressed
> ---------------------------------------------
>
>                 Key: HDFS-1435
>                 URL: https://issues.apache.org/jira/browse/HDFS-1435
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: name-node
>    Affects Versions: 0.22.0
>            Reporter: Hairong Kuang
>            Assignee: Hairong Kuang
>             Fix For: 0.22.0
>
>
> Our HDFS has fsimage as big as 20G bytes. It consumes a lot of network 
> bandwidth when secondary NN uploads a new fsimage to primary NN.
> If we could store fsimage compressed, the problem could be greatly alleviated.
> I plan to provide a new configuration hdfs.image.compressed with a default 
> value of false. If it is set to be true, fsimage is stored as compressed.
> The fsimage will have a new layout with a new field "compressed" in its 
> header, indicating if the namespace is stored compressed or not.

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