external-software/github_OpenIdentityPlatform_OpenDJ.git

			@@ -114,6 +114,9 @@
			in the setup wizard, read this section to learn more about how OpenDJ
			replication works.</para>

			<section xml:id="repl-what-it-is">
			<title>What Replication Is</title>

			<para>Replication is the process of copying updates between OpenDJ
			directory servers such that all servers converge on identical copies of
			directory data. Replication is designed to let convergence happen over
			@@ -137,6 +140,15 @@
			ensure that you do not purge the historical information more often than you
			backup your directory data.</para>

			<para>Keep server clocks synchronized for your topology. You can use NTP for
			example. Keeping server clocks synchronized helps prevent issues with SSL
			connections and with replication itself. Keeping server clocks synchronized
			also makes it easier to compare timestamps from multiple servers.</para>
			</section>

			<section xml:id="repl-per-suffix">
			<title>Replication Per Suffix</title>

			<para>The primary unit of replication is the suffix, specified by a
			base DN such as <literal>dc=example,dc=com</literal>.<footnote><para>When
			you configure partial and fractional replication, however, you can replicate
			@@ -188,11 +200,112 @@
			connected for <literal>dc=example,dc=org</literal>.</para>
			</textobject>
			</mediaobject>
			</section>

			<para>Keep server clocks synchronized for your topology. You can use NTP for
			example. Keeping server clocks synchronized helps prevent issues with SSL
			connections and with replication itself. Keeping server clocks synchronized
			also makes it easier to compare timestamps from multiple servers.</para>
			<section xml:id="repl-connection-selection">
			<title>Replication Connection Selection</title>

			<para>In order to understand what happens when individual servers stop
			responding due to a network partition or a crash, know that OpenDJ can
			offer both directory service and also replication service, and the two
			services are not the same, even if they can run alongside each other in
			the same OpenDJ server in the same Java Virtual Machine.</para>

			<para>Replication relies on the replication service provided by OpenDJ
			replication servers, where OpenDJ directory servers publish changes made
			to their data, and subscribe to changes published by other OpenDJ directory
			servers. A replication server manages replication data only, handling
			replication traffic with directory servers and with other replication
			servers, receiving, sending, and storing only changes to directory data
			rather than directory data itself. Once a replication server is connected
			to a replication topology, it maintains connections to all other
			replication servers in that topology.</para>

			<para>A directory server handles directory data. It responds to requests,
			stores directory data and historical information. For each replicated
			suffix, such as <literal>dc=example,dc=com</literal>,
			<literal>cn=schema</literal> and <literal>cn=admin data</literal>, the
			directory server publishes changes to a replication server, and subscribes
			to changes from that replication server. (Directory servers do not publish
			changes to other directory servers.) A directory server also resolves any
			conflicts that arise when reconciling changes from other directory servers,
			using the historical information about changes to resolve the conflicts.
			(Conflict resolution is the responsibility of the directory server rather
			than the replication server.)</para>

			<para>Once a directory server is connected to a replication topology for a
			particular suffix, it connects to one replication server at a time for that
			suffix. The replication server provides the directory server with a list of
			all replication servers for that suffix. Given the list of possible
			replication servers to which it can connect, the directory server can
			determine which replication server to connect to when starting up, or when
			the current connection is lost or becomes unresponsive.</para>

			<orderedlist>
			<para>For each replicated suffix, a directory server prefers to connect to
			a replication server:</para>

			<listitem>
			<para>In the same group as the directory server</para>
			</listitem>

			<listitem>
			<para>Having the same initial data for the suffix as the directory
			server</para>
			</listitem>

			<listitem>
			<para>If initial data were the same, having all the latest changes from
			the directory server</para>
			</listitem>

			<listitem>
			<para>Running in the same Java Virtual Machine as the directory
			server</para>
			</listitem>

			<listitem>
			<para>Having the most available capacity relative to other eligible
			replication servers</para>

			<para>Available capacity depends on how many directory servers in the
			topology are already connected to a replication server, and what
			proportion of all directory servers in the topology ought to be connected
			to the replication server.</para>

			<para>To determine what proportion of the total number of directory
			servers should be connected to a replication server, OpenDJ uses
			replication server weight. When configuring a replication server, you
			can assign it a weight (default: 1). The weight property takes an integer
			that indicates capacity to provide replication service relative to other
			servers. For example, a weight of 2 would indicate a replication server
			that can handle twice as many connected servers as a replication server
			with weight 1.</para>

			<para>The proportion of directory servers in a topology that should be
			connected to a given replication server is equal to (replication server
			weight)/(sum of replication server weights). In other words, if there are
			4 replication servers in a topology each with default weights, the
			proportion for each replication server is 1/4.</para>
			</listitem>
			</orderedlist>

			<para>Consider a situation where 7 directory servers are connected to
			replication servers A, B, C, and D for <literal>dc=example,dc=com</literal>
			data. Suppose 2 directory servers each are connected to A, B, and C, and 1
			directory server is connected to replication server D. Replication server D
			is therefore the server with the most available capacity relative to other
			replication servers in the topology. All other criteria being equal,
			replication server D is the server to connect to when an 8th directory
			server joins the topology.</para>

			<para>The directory server regularly updates the list of replication servers
			in case it must reconnect. As available capacity of replication servers for
			each replication topology can change dynamically, a directory server can
			potentially reconnect to another replication server to balance the
			replication load in the topology. For this reason the server can also end
			up connected to different replication servers for different suffixes.</para>
			</section>
			</section>

			<section xml:id="configure-repl">