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https://issues.apache.org/jira/browse/HDFS-6339?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13989711#comment-13989711
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Rahul Singhal commented on HDFS-6339:
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Thanks a lot for your reply [~kihwal].
I was testing both cases/paths:
(non-HA, 2.2.0) -> (non-HA, 2.4.0) -> (non-HA 2.2.0)
(HA, 2.2.0) -> (HA, 2.4.0) -> (non-HA, 2.2.0) -> (HA, 2.2.0)
The issue with 2NN was noticed in cases 1. I guess I was mainly confused by the
fact that start-dfs.sh does not fromat the 2NN during rollback.
Thanks for confirming my procedure. And I will use the mailing list for future
questions but since you have the context here, I was hoping you could answer
one more questions. In what cases, will NN not have all edits locally? Should
they be available at edits.dir?
> DN, SNN & JN can't rollback data
> --------------------------------
>
> Key: HDFS-6339
> URL: https://issues.apache.org/jira/browse/HDFS-6339
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: journal-node
> Affects Versions: 2.2.0
> Reporter: Rahul Singhal
>
> I tried rollback from 2.4.0 to 2.2.0 and noticed that DN, SNN and JN couldn't
> perform rollback.
> I started with a (NN) HA cluster on 2.2.0 and upgraded it to 2.4.0 with HA
> enabled. Then attempted a rollback to 2.2.0. I first configured my cluster to
> non-HA and started it on 2.2.0. I started NN & DN with the '-rollback'
> startup option. (There is no explicit startup option for SNN & JN like NN &
> DN). Only NN was able to rollback correctly.
> My fixes:
> I fixed the DN rollback problem by cherry-picking the fix from HDFS-5526.
> I fixed the SNN rollback problem by starting it with '-format' option.
> I then proceeded to converting the non-HA cluster to a HA cluster. The first
> step after configuration change was to start the JNs. But they also couldn't
> rollback.
> My fix:
> I fixed this by deleting the JN data directory. (deleting the 'current'
> directory and renaming 'previous' to 'current' didn't fix the rollback)
> My purpose for filing this bug is to:
> 1. Ask if these problems are known and intended to be fixed in any future
> releases. If yes, which one? DN rollback was fixed in 2.3.0 but what about
> 2.2.x series? JN rollback seems (not confirmed) to have been fixed in 2.4.0.
> 2. Confirm that "my fixes" are correct. If not, please help me with an
> appropriate fix.
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