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https://issues.apache.org/jira/browse/HDFS-8578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14589296#comment-14589296
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Vinayakumar B commented on HDFS-8578:
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Just realized that, parallelism should be added at the datanode level in
{{DataStorage#addStorageLocations()}}. Not in the BlockPoolSliceStorage.
{{BlockPoolSliceStorage#loadBpStorageDirectories()}} called sequentially for
each datadir during startup in {{DataStorage#addStorageLocations()}}
And during startup, If any one of the blockpool storage directories failed to
load/upgrade also, datanode continues to start with other directories
available. Only if all directories are failed to load then only it will fail.
> On upgrade, Datanode should process all storage/data dirs in parallel
> ---------------------------------------------------------------------
>
> Key: HDFS-8578
> URL: https://issues.apache.org/jira/browse/HDFS-8578
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Reporter: Raju Bairishetti
> Priority: Critical
> Attachments: HDFS-8578-01.patch
>
>
> Right now, during upgrades datanode is processing all the storage dirs
> sequentially. Assume it takes ~20 mins to process a single storage dir then
> datanode which has ~10 disks will take around 3hours to come up.
> *BlockPoolSliceStorage.java*
> {code}
> for (int idx = 0; idx < getNumStorageDirs(); idx++) {
> doTransition(datanode, getStorageDir(idx), nsInfo, startOpt);
> assert getCTime() == nsInfo.getCTime()
> : "Data-node and name-node CTimes must be the same.";
> }
> {code}
> It would save lots of time during major upgrades if datanode process all
> storagedirs/disks parallelly.
> Can we make datanode to process all storage dirs parallelly?
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