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https://issues.apache.org/jira/browse/HADOOP-3328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Lohit Vijayarenu updated HADOOP-3328:
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Description:
Currently all the datanodes in DFS write pipeline verify checksum. Since the
current protocol includes acks from the datanodes, an ack from the last node
could also serve as verification that checksum ok. In that sense, only the last
datanode needs to verify checksum. Based on [this
comment|http://issues.apache.org/jira/browse/HADOOP-1702?focusedCommentId=12575553#action_12575553]
from HADOOP-1702, CPU consumption might go down by another 25-30% (4/14) after
HADOOP-1702.
Also this would make it easier to use transferTo() and transferFrom() on
intermediate datanodes since they don't need to look at the data.
was:
Currently all the datanodes in DFS write pipeline verify checksum. Since the
current protocol includes acks from the datanodes, an ack from the last node
could also serve as verification that checksum ok. In that sense, only the last
datanode needs to verify checksum. Based on [this
comment|http://issues.apache.org/jira/browse/HADOOP-1702?focusedCommentId=12575553#action_12575553]
from HADOOP-1702, CPU consumption might go down by another 25-30% (4/14) after
HADOOP-1702.
Also this would make it easier to use transferTo() and transferFrom() on
intermediate datanodes since they don't need to look at the data.
Hadoop Flags: [Reviewed]
+1 Looks good.
> DFS write pipeline : only the last datanode needs to verify checksum
> --------------------------------------------------------------------
>
> Key: HADOOP-3328
> URL: https://issues.apache.org/jira/browse/HADOOP-3328
> Project: Hadoop Core
> Issue Type: Improvement
> Components: dfs
> Affects Versions: 0.16.0
> Reporter: Raghu Angadi
> Assignee: Raghu Angadi
> Attachments: HADOOP-3328.patch, HADOOP-3328.patch
>
>
> Currently all the datanodes in DFS write pipeline verify checksum. Since the
> current protocol includes acks from the datanodes, an ack from the last node
> could also serve as verification that checksum ok. In that sense, only the
> last datanode needs to verify checksum. Based on [this
> comment|http://issues.apache.org/jira/browse/HADOOP-1702?focusedCommentId=12575553#action_12575553]
> from HADOOP-1702, CPU consumption might go down by another 25-30% (4/14)
> after HADOOP-1702.
> Also this would make it easier to use transferTo() and transferFrom() on
> intermediate datanodes since they don't need to look at the data.
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