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Anoop Sam John commented on HBASE-24601: ---------------------------------------- Better we can mark this as an incompatible change? This changes a behaviour even though we call old behave as bug or not. > 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: HFile > Affects Versions: 2.2.5 > Reporter: dark_num > Assignee: dark_num > Priority: Major > Fix For: 2.5.0, 3.0.0-alpha-2 > > 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 -- This message was sent by Atlassian Jira (v8.3.4#803005)