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https://issues.apache.org/jira/browse/HDFS-5851?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14034632#comment-14034632
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Sanjay Radia commented on HDFS-5851:
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Colin wrote:
bq. why a separate namespace under hdfs://<namespace>/.reserved/ddm ? We have
xattrs now, so files ...
I did not explain it well. It is a separation of policy and mechanism. HDFS has
to support such files for ANY name. Hence we can use xattr to create files
write cache.
The policy of managing the memory space and the underlying swap space (e.g.
hdfs://namepace/.reserved/ddm) is separate from the write-cache mechanism that
HDFS needs to support in ANY part of its namespace; so I believe we are in
agreement here. I will explain the policy I am proposing in a separate comment.
> Support memory as a storage medium
> ----------------------------------
>
> Key: HDFS-5851
> URL: https://issues.apache.org/jira/browse/HDFS-5851
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode
> Affects Versions: 3.0.0
> Reporter: Arpit Agarwal
> Assignee: Arpit Agarwal
> Attachments:
> SupportingMemoryStorageinHDFSPersistentandDiscardableMemory.pdf,
> SupportingMemoryStorageinHDFSPersistentandDiscardableMemory.pdf
>
>
> Memory can be used as a storage medium for smaller/transient files for fast
> write throughput.
> More information/design will be added later.
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