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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (GEODE-2994) Doc task: interactions of backups with persistence
Date Wed, 31 May 2017 18:41:04 GMT

    [ https://issues.apache.org/jira/browse/GEODE-2994?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16031667#comment-16031667
] 

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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