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https://issues.apache.org/jira/browse/HDFS-6934?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14158840#comment-14158840
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Tsz Wo Nicholas Sze commented on HDFS-6934:
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We have the following cases in datanode side when receiving a packet:
|| No Checksum Received || Writing to Transient Storage || Action ||
| T | T | No checksum is stored |
| T | F | Compute checksum and write to disk |
| F | T | Write checksum to memory |
| F | F | Write checksum to disk |
> Move checksum computation off the hot path when writing to RAM disk
> -------------------------------------------------------------------
>
> Key: HDFS-6934
> URL: https://issues.apache.org/jira/browse/HDFS-6934
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode
> Reporter: Arpit Agarwal
> Assignee: Tsz Wo Nicholas Sze
>
> Since local RAM is considered reliable we can avoid writing checksums on the
> hot path when replicas are being written to a local RAM disk.
> The checksum can be computed by the lazy writer when moving replicas to disk.
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