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https://issues.apache.org/jira/browse/HDFS-10800?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15509035#comment-15509035
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Rakesh R commented on HDFS-10800:
---------------------------------
Thanks [~umamaheswararao], latest patch looks good. Few more suggestions to
improve the patch. sorry, I failed to identify this in my previous review,
would you mind incorporating this.
# We could mark the new classes {{@InterfaceAudience.Private}}
# Can we find a better name for ‘StorageMovementNeeded’ class, this name looks
like its moving the storage. How about BlockMovementNeeded or
BlockStorageMovementNeeded?
# It would be good if we could {{sps.stop();}} the thread at the beginning of
the {{BlockManager#stop()}} function. This could avoid unwanted exceptions in
future if someone add extra codes which depends on already stopped dependent
services
# IMHO, {{#assignStorageMovementTasksToDN()}} can be moved inside
{{#buildStorageMismatchedBlocks(long blockCollectionID)}}, that way we could
avoid passing few args. Also, the below if condition is not required as
duplicate checks inside the assign function, right?
{code}
if (blockInfoToMoveStorages.size() > 0) {
assignStorageMovementTasksToDN(coordinatorNode,
blockCollectionID,
blockInfoToMoveStorages);
}
{code}
# Also, can you make the following variable as {{final}}. This will avoid NPE
if someone mistakenly do any changes in future.
{code}
private StoragePolicySatisfier sps;
private StorageMovementNeededneedStorageMovement = newStorageMovementNeeded();
{code}
> [SPS]: Storage Policy Satisfier daemon thread in Namenode to find the blocks
> which were placed in other storages than what NN is expecting.
> -------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-10800
> URL: https://issues.apache.org/jira/browse/HDFS-10800
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Affects Versions: HDFS-10285
> Reporter: Uma Maheswara Rao G
> Assignee: Uma Maheswara Rao G
> Attachments: HDFS-10800-HDFS-10285-00.patch,
> HDFS-10800-HDFS-10285-01.patch, HDFS-10800-HDFS-10285-02.patch,
> HDFS-10800-HDFS-10285-03.patch
>
>
> This JIRA is for implementing a daemon thread called StoragePolicySatisfier
> in nematode, which should scan the asked files blocks which were placed in
> wrong storages in DNs.
> The idea is:
> # When user called on some files/dirs for satisfyStorage policy, They
> should have tracked in NN and then StoragePolicyDaemon thread will pick one
> by one file and then check the blocks which might have placed in wrong
> storage in DN than what NN is expecting it to.
> # After checking all, it should also construct the data structures for
> the required information to move a block from one storage to another.
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