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https://issues.apache.org/jira/browse/GEODE-2994?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16031734#comment-16031734
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ASF GitHub Bot commented on GEODE-2994:
---------------------------------------

Github user dihardman commented on a diff in the pull request:

    https://github.com/apache/geode/pull/544#discussion_r119445495
  
    --- Diff: geode-docs/tools_modules/lucene_integration.html.md.erb ---
    @@ -294,8 +294,11 @@ will return `object_2`.
     will return `object_3`.
     - Backups should only be made for regions with Lucene indexes
     when there are no puts, updates, or deletes in progress.
    -Incremental backups will not be consistent for the region and
    -its index upon restart if these operations were in progress,
    -due to the delayed processing associated with the asynchronous event queue.
    -If region data needs to be restored from a backup,
    -follow the same procedure as given for changing an index.
    +A backup might cause an inconsistency between region data and a Lucene 
index,
    +if that backup is used to restore a system.
    +The Lucene index is persistent.
    +If a backup is unlucky enough to be taken between
    +a persisted write to a region (causing a disk operation)
    +and the resulting persisted write to the Lucene index
    +(causing a disk operation),
    +then the backup represents inconsistent data in the region and Lucene 
index.
    --- End diff --
    
    See comments added to backup_restore_disk_store.erb


> Doc task: interactions of backups with persistence
> --------------------------------------------------
>
>                 Key: GEODE-2994
>                 URL: https://issues.apache.org/jira/browse/GEODE-2994
>             Project: Geode
>          Issue Type: Improvement
>          Components: docs
>            Reporter: Karen Smoler Miller
>            Assignee: Karen Smoler Miller
>
> Document that an inconsistent state can occur by using a backup to restore 
> system state, if the backup is made at the wrong time.
> There are 2 examples where persistence and taking a backup might cause an 
> inconsistency with region data, if that backup is used to restore a system.
> # *A Lucene index.* The Lucene index is persistent. If a backup is unlucky 
> enough to be taken between a persisted write to a region (disk op) and a 
> persisted write to the Lucene index (disk op), then the backup represents 
> inconsistent data in the region and Lucene index.
> # *An AEQ.* The AEQ is persistent. If a backup is unlucky enough to be taken 
> between a persisted write to a region (disk op) and a persisted write to the 
> AEQ (disk op), then the backup represents inconsistent data in the region and 
> the AEQ.
> The solution is to make sure that backups are taken when the system is 
> quiescent WRT region operations.



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