From ff4b6003d832c53112a514d9df8425c644e7e81f Mon Sep 17 00:00:00 2001
From: Mark Craig <mark.craig@forgerock.com>
Date: Fri, 22 Jun 2012 06:31:15 +0000
Subject: [PATCH] Explain why to use a backup newer than the replication purge delay when restoring a replica
---
opendj3/src/main/docbkx/admin-guide/chap-backup-restore.xml | 27 +++++++++++++++++++++++----
1 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/opendj3/src/main/docbkx/admin-guide/chap-backup-restore.xml b/opendj3/src/main/docbkx/admin-guide/chap-backup-restore.xml
index eb18547..2046dbb 100644
--- a/opendj3/src/main/docbkx/admin-guide/chap-backup-restore.xml
+++ b/opendj3/src/main/docbkx/admin-guide/chap-backup-restore.xml
@@ -188,10 +188,29 @@
<secondary>Restoring from backup</secondary>
</indexterm>
- <para>When you restore a replicated server from backup, make sure the
- backup is newer than the last purge of the replication change log (default:
- 3 days).</para>
-
+ <para>After you restore a replica from backup, replication brings the replica
+ up to date with changes that happened after you created the backup. In order
+ to bring the replica up to date, replication must apply changes that
+ happened after the backup was made. Replication uses internal change log
+ records to determine what changes to apply.</para>
+
+ <para>Internal change log records are no kept forever, though. Replication
+ is configured to purge the change log of old changes, preventing the log
+ from growing indefinitely. Yet, for replication to determine what changes
+ to apply to a restored replica, it must find change log records dating back
+ at least to the last change in the backup. In other words, replication can
+ bring the restored replica up to date <emphasis>as long as the change log
+ records used to determine which changes to apply have not been
+ purged</emphasis>.</para>
+
+ <para>Therefore, when you restore a replicated server from backup, make sure
+ the backup you use is newer than the last purge of the replication change
+ log (default: 3 days). If all your backups are older than the replication
+ purge delay, do not restore from a backup, but instead initialize a new
+ replica as described in <link xlink:href="admin-guide#init-repl"
+ xlink:role="http://docbook.org/xlink/role/olink"><citetitle>Initializing
+ Replicas</citetitle></link>.</para>
+
<step>
<para>Prepare the replica to be restored.</para>
<screen>$ dsreplication
--
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