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https://issues.apache.org/jira/browse/HDFS-8401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14544138#comment-14544138
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Bikas Saha commented on HDFS-8401:
----------------------------------

I am guessing that anything that is written to in-memory storage via memfs 
would also be read back in-memory via memfs. The centralized cache management 
is not the only in-memory read path, right?

> Memfs - a layered file system for in-memory storage in HDFS
> -----------------------------------------------------------
>
>                 Key: HDFS-8401
>                 URL: https://issues.apache.org/jira/browse/HDFS-8401
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Arpit Agarwal
>            Assignee: Arpit Agarwal
>
> We propose creating a layered filesystem that can provide in-memory storage 
> using existing features within HDFS. memfs will use lazy persist writes 
> introduced by HDFS-6581. For reads, memfs can use the Centralized Cache 
> Management feature introduced in HDFS-4949 to load hot data to memory.
> Paths in memfs and hdfs will correspond 1:1 so memfs will require no 
> additional metadata and it can be implemented entirely as a client-side 
> library.
> The advantage of a layered file system is that it requires little or no 
> changes to existing applications. e.g. Applications can use something like 
> {{memfs://}} instead of {{hdfs://}} for files targeted to memory storage. 



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