[jira] [Commented] (HBASE-24601) Change default Hfile storage policy from HOT to NONE for HDFS

["dark_num (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-24601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17156241#comment-17156241 ] 

dark_num commented on HBASE-24601:
----------------------------------

Due to there has been no new reply/review for some time.

[~Ddupg] , [~comnetwork], [~skewdata], could you take a look at it? 

> Change default Hfile storage policy from HOT to NONE for HDFS
> -------------------------------------------------------------
>
>                 Key: HBASE-24601
>                 URL: https://issues.apache.org/jira/browse/HBASE-24601
>             Project: HBase
>          Issue Type: Bug
>          Components: hadoop3, HFile
>    Affects Versions: 2.2.5
>            Reporter: dark_num
>            Priority: Major
>         Attachments: hfile-policy-problem.png
>
>
> The current HBase hfile directory specifies the *HOT* storage strategy by default(`hbase.hstore.blockingStoreFiles` ), which is different from the default value of HDFS *heterogeneous* strategy now(should be empty)
> It should be set to *NONE* like `hbase.wal.storage.policy`'s default value on HBASE-20691, and the reason for modification is the same
> Otherwise, it could have a significant impact because most HDFS Managers doesn't know the default value has been changed to *HOT* by hbase, for example:
> HDFS manger want to set hfile's dir to ONE_SSD for speed up read, they will do:
> {code:java}
> // Set Hbas Hfile dir to ONE_SSD for speed up read
> // The policy that expects all subdirectories to inherit the parent directory by default (empty by default)
> bin/hdfs storagepolicies -setStoragePolicy -path /home/hbase/data  -policy ONE_SSD
> bin/hdfs storagepolicies -setStoragePolicy -path /home/hbase/WALs  -policy ALL_SSD
> // If we do not change Hbase default setting, we will find this
> bin/hdfs storagepolicies -getStoragePolicy -path /home/hbase/data/hbase/meta/xxxx/info 
> return "HOT" instead of "ONE_SSD"{code}
> And here is a pic to show the problem ↑:
>   !hfile-policy-problem.png!
> However, if Hfile uses the *HOT* strategy by default, then we will find that the actually stored directory has been set to HOT, then it will *not inherit* the *ONE_SSD* of the parent directory policy, and if we set *NONE* in hbase, this is problem can be avoided
>  Unless someone sets other values manually, then we believe the operator knows what he is doing



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