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https://issues.apache.org/jira/browse/GEODE-2994?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16032017#comment-16032017
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ASF GitHub Bot commented on GEODE-2994:
---------------------------------------
Github user karensmolermiller commented on a diff in the pull request:
https://github.com/apache/geode/pull/544#discussion_r119481660
--- 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 --
Reworded.
> 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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