[jira] [Commented] (BOOKKEEPER-150) Entry is lost when recovering a ledger with not enough bookies.

["Flavio Junqueira (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BOOKKEEPER-150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13179063#comment-13179063 ] 

Flavio Junqueira commented on BOOKKEEPER-150:
---------------------------------------------

I agree, it sounds wrong to close the ledger in that case.
                
> Entry is lost when recovering a ledger with not enough bookies.
> ---------------------------------------------------------------
>
>                 Key: BOOKKEEPER-150
>                 URL: https://issues.apache.org/jira/browse/BOOKKEEPER-150
>             Project: Bookkeeper
>          Issue Type: Bug
>          Components: bookkeeper-client
>    Affects Versions: 4.0.0
>            Reporter: Sijie Guo
>            Assignee: Sijie Guo
>             Fix For: 4.1.0
>
>         Attachments: BOOKKEEPER-150.patch
>
>
> suppose a ledger is created as ensemble size 3 and quorum size 3.
> 3 entries is added in this ledger, entry ids are 0, 1, 2.
> this ledger is not closed. then a bookie server is down.
> the ledger is opened. it would be recovered in following steps:
> 1) retrieve LAC from all bookie ensemble to get maxAddConfirmed. then maxAddPushed would be 2 and maxAddConfirmed would be 1. then lastAddConfirmed would be 1.
> 2) doRecovery read lastAddConfirmed + 1 (2). it would return right data since there is still 2 replicas.
> 3) doRecovery add entry 2. but it would fail since there is not enough bookies to form a new ensemble.
> 4) this ledger will be closed with lastAddConfirmed (1). entry 2 will be lost.
> this issue happened in hub server. old ledger will be recovered and closed when changing ownership. so published messages would be lost.
> we should not close ledger when we encountered exception during recovery adding, otherwise we would lose entries.

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