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https://issues.apache.org/jira/browse/HDFS-11464?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yiqun Lin updated HDFS-11464:
-----------------------------
Description:
Currently the logic in choosing storage for blocks is not a good way. It always
uses the first valid storage of a given StorageType ({{see
DataNodeDescriptor#chooseStorage4Block}}). This should not be a good selection.
That means blcoks will always be written to the same volume (first volume) and
other valid volumes have no choices. This problem is brought up by this comment
(
https://issues.apache.org/jira/browse/HDFS-9807?focusedCommentId=15878382&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15878382
)
There is one solution from me:
* First, based on existing storages in one node, extract all the valid storages
into a collection.
* Then, disrupt the order of these vaild storages, get a new collection.
* Finally, get the first storage from the new storages collection.
These steps will be executed in {{DataNodeDescriptor#chooseStorage4Block}} and
replace current logic. I think this improvement can be done as a subtask under
HDFS-11419. Any further comments are welcomed.
was:
Currently the logic in choosing storage for blocks is not a good way. It always
uses the first valid storage of a given StorageType ({{see
DataNodeDescriptor#chooseStorage4Block}}). This should not be a good selection.
That means blcoks will always be written to the same volume (first volume)
until this volume has not available space. This problem is brought up by this
comment (
https://issues.apache.org/jira/browse/HDFS-9807?focusedCommentId=15878382&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15878382
)
There is one solution from me:
* First, based on existing storages in one node, extract all the valid storages
into a collection.
* Then, disrupt the order of these vaild storages, get a new collection.
* Finally, get the first storage from the new storages collection.
These steps will be executed in {{DataNodeDescriptor#chooseStorage4Block}} and
replace current logic. I I think this improvement can be done as a subtask
under HDFS-11419. Any further comments are welcomed.
> Improve the selection in choosing storage for blocks
> ----------------------------------------------------
>
> Key: HDFS-11464
> URL: https://issues.apache.org/jira/browse/HDFS-11464
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Yiqun Lin
> Assignee: Yiqun Lin
>
> Currently the logic in choosing storage for blocks is not a good way. It
> always uses the first valid storage of a given StorageType ({{see
> DataNodeDescriptor#chooseStorage4Block}}). This should not be a good
> selection. That means blcoks will always be written to the same volume (first
> volume) and other valid volumes have no choices. This problem is brought up
> by this comment (
> https://issues.apache.org/jira/browse/HDFS-9807?focusedCommentId=15878382&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15878382
> )
> There is one solution from me:
> * First, based on existing storages in one node, extract all the valid
> storages into a collection.
> * Then, disrupt the order of these vaild storages, get a new collection.
> * Finally, get the first storage from the new storages collection.
> These steps will be executed in {{DataNodeDescriptor#chooseStorage4Block}}
> and replace current logic. I think this improvement can be done as a subtask
> under HDFS-11419. Any further comments are welcomed.
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