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https://issues.apache.org/jira/browse/HDFS-1108?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12881980#action_12881980
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Suresh Srinivas commented on HDFS-1108:
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I have few questions about this change:
# Which persistBlocks() are referring to? Does this mean block information is
persisted twice - first time when it was created and second time when the file
is closed to record the real block size?
# Given that a block is recorded during creation, how does namenode handle
these blocks during restart, if the block was never written to the datanode?
# Should this be a HA related change where primary namenode flags this to
standby instead of using editlogs written to the disk?
> ability to create a file whose newly allocated blocks are automatically
> persisted immediately
> ---------------------------------------------------------------------------------------------
>
> Key: HDFS-1108
> URL: https://issues.apache.org/jira/browse/HDFS-1108
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: name-node
> Reporter: dhruba borthakur
> Assignee: Dmytro Molkov
> Attachments: HDFS-1108.patch
>
>
> The current HDFS design says that newly allocated blocks for a file are not
> persisted in the NN transaction log when the block is allocated. Instead, a
> hflush() or a close() on the file persists the blocks into the transaction
> log. It would be nice if we can immediately persist newly allocated blocks
> (as soon as they are allocated) for specific files.
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