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https://issues.apache.org/jira/browse/HDFS-8578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15052152#comment-15052152
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Vinayakumar B commented on HDFS-8578:
-------------------------------------
Synchronization on {{DataStorage}} will affect only for this part of the code,
which basically does the formatting/loading version file in datanode level.
Since data loaded from version file will be same accross all VERSION file, it
should not matter.
{nofomat} File root = dataDir.getFile();
try {
if (!containsStorageDir(root)) {
// It first ensures the datanode level format is completed.
StorageDirectory sd = loadStorageDirectory(datanode, nsInfo,
root, startOpt);
addStorageDir(sd);
} else {
LOG.info("Storage directory " + dataDir
+ " has already been used.");
}
} catch (IOException e) {
LOG.warn("Failed to add Storage directory " + dataDir, e);
return null;
}{noformat}
Earlier, getDatanodeUuid() was called, which was getting blocked, so only I had
removed synchronization on {{addStorageLocations()}}.
Still I believe there should not be any problem with synchronization.
Only thing is, since I have restored synchronizarion on addStorageLocations(),
synchronization on {{DataStorage#setFieldsFromProperties(..)}} is removed in
latest patch. Still since all values are same values, there should not be any
problem with this.
> 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
> Assignee: Vinayakumar B
> Priority: Critical
> Attachments: HDFS-8578-01.patch, HDFS-8578-02.patch,
> HDFS-8578-03.patch, HDFS-8578-04.patch, HDFS-8578-05.patch,
> HDFS-8578-06.patch, HDFS-8578-07.patch, HDFS-8578-08.patch,
> HDFS-8578-09.patch, HDFS-8578-10.patch, HDFS-8578-11.patch,
> HDFS-8578-12.patch, HDFS-8578-13.patch, HDFS-8578-14.patch,
> HDFS-8578-15.patch, HDFS-8578-16.patch, HDFS-8578-branch-2.6.0.patch,
> HDFS-8578-branch-2.7-001.patch, HDFS-8578-branch-2.7-002.patch,
> HDFS-8578-branch-2.7-003.patch, h8578_20151210.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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