[jira] [Commented] (ZOOKEEPER-1149) users cannot migrate from 3.4->3.3->3.4 server code against a single datadir

["Mahadev konar (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13084941#comment-13084941 ] 

Mahadev konar commented on ZOOKEEPER-1149:
------------------------------------------

Pat,
 Should we add this to the release notes? Anything else you think we should do regarding this jira?

> users cannot migrate from 3.4->3.3->3.4 server code against a single datadir
> ----------------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-1149
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1149
>             Project: ZooKeeper
>          Issue Type: Task
>          Components: server
>    Affects Versions: 3.4.0
>            Reporter: Patrick Hunt
>            Priority: Blocker
>             Fix For: 3.4.0
>
>
> 3.4 is checking acceptedEpoch/currentEpoch files against the snap/log files in datadir. These files are new in 3.4. If they don't exist the server will create them, however if they do exist the server will validate them.
> As a result if a user 
> 1) upgrades from 3.3 to 3.4 this is fine
> 2) downgrades from 3.4 to 3.3 this is also fine (3.3 ignores these files)
> 3) however, 3.4->3.3->3.4 fails because 3.4 will see invalid *Epoch files in the datadir (as 3.3 would have ignored them, applying changes to snap/log w/o updating them)

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