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https://issues.apache.org/jira/browse/GEODE-2994?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16031667#comment-16031667
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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_r119439870
--- Diff:
geode-docs/managing/disk_storage/backup_restore_disk_store.html.md.erb ---
@@ -38,6 +38,15 @@ Do not try to create backup files from a running system
by using your operating
**Preparing to Make a Backup**
- Consider compacting your disk store before making a backup. If
auto-compaction is turned off, you may want to do a manual compaction to save
on the quantity of data copied over the network by the backup. For more
information on configuring a manual compaction, see [Manual
Compaction](compacting_disk_stores.html#compacting_disk_stores__li_63CF8C35153D4173AADF7DC35FEC61F9).
+- Take the backup when region operations are quiescent,
+to avoid the possibility of an inconsistency between region data and
+an asyncronous event queue (AEQ),
+if that backup were to be used to restore a system.
+The AEQ is persistent.
+If a backup is unlucky enough to be taken between
--- End diff --
Instead of "If the backup is unlucky enough to be taken between", consider:
If the timing of the backup occurs between...
> 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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