Document how to move from single to cluster (#891)

modules/ROOT/content-nav.adoc

@@ -119,6 +119,7 @@
 ** Set up a cluster
 *** xref:clustering/setup/deploy.adoc[]
 *** xref:clustering/setup/analytics-cluster.adoc[]
+*** xref:clustering/setup/single-to-cluster.adoc[]
 *** xref:clustering/setup/discovery.adoc[]
 *** xref:clustering/setup/routing.adoc[]
 *** xref:clustering/setup/encryption.adoc[]

modules/ROOT/pages/clustering/index.adoc

@@ -9,6 +9,7 @@ This chapter describes the following:
 * Set up a cluster -- The basics of configuring and deploying a new cluster.
 ** xref:clustering/setup/deploy.adoc[Deploy a basic cluster] -- How to set up a basic cluster.
 ** xref:clustering/setup/analytics-cluster.adoc[Deploy an analytics cluster] -- How to deploy a special case Neo4j cluster for analytic queries.
+** xref:clustering/setup/single-to-cluster.adoc[Move from single server to cluster] -- This section describes how to move from a single Neo4j server to Neo4j cluster.
 ** xref:clustering/setup/discovery.adoc[Cluster server discovery] -- How servers in a cluster discover each other.
 ** xref:clustering/setup/routing.adoc[Leadership, routing and load balancing] -- Election of leaders, routing and load balancing.
 ** xref:clustering/setup/encryption.adoc[Intra-cluster encryption] -- How to secure the cluster communication.

modules/ROOT/pages/clustering/setup/single-to-cluster.adoc

@@ -0,0 +1,77 @@
+:description: This section describes how to move from a standalone deployment to a cluster.
+[role=enterprise-edition]
+[[single-to-cluster]]
+= Move from a standalone deployment to a cluster
+
+It is possible to move from a standalone deployment with a single `system` database to a cluster with multiple `system` primaries.
+In essence, this is done by dumping the `system` database from the standalone server and loading it into the other servers that are to form the cluster.
+The following example shows how to move from a standalone server with a single `system` primary to a cluster with three `system` primaries.
+
+[NOTE]
+====
+Another deployment with a single `system` database is an **analytics cluster** with a single `system` primary.
+If desired to move to a cluster with multiple `system` primaries, the following example is applicable with the addition that the secondaries are discarded (this is done in the first step when the `neo4j.conf` file is modified).
+See xref:clustering/setup/analytics-cluster.adoc[] for more information on analytics clusters.
+====
+
+.Move from a single `system` database to a cluster with three `system` primaries
+====
+In this example, a standalone server named `server01` is running and two additional servers, `server02` and `server03`, are to be added to form a cluster.
+The two additional servers are configured according to xref:clustering/setup/deploy.adoc#cluster-example-configure-a-three-primary-cluster[Configure a cluster with three servers] and are _not_ running.
+Neo4j Enterprise Edition is installed on all three servers.
+
+Start by stopping the standalone server and once it is stopped, edit the xref:configuration/file-locations.adoc[_neo4j.conf_] file to include the discovery endpoints of itself and the servers that will form the cluster.
+
+._neo4j.conf_ on server01.example.com:
+[source, properties]
+----
+server.default_listen_address=0.0.0.0
+server.default_advertised_address=server01.example.com
+dbms.cluster.discovery.endpoints=server01.example.com:5000,server02.example.com:5000,server03.example.com:5000
+initial.dbms.default_primaries_count=3
+----
+(The xref:configuration/file-locations.adoc[_neo4j.conf_] file looks identical except for the `server.default_advertised_address` on all three servers. Please refer to xref:clustering/setup/deploy.adoc#cluster-example-configure-a-three-primary-cluster[Configure a cluster with three servers] for more information.)
+
+On `server01` (the standalone server) dump the `system` database using the `neo4j-admin database dump` command.
+
+[source, shell, role="nocopy"]
+----
+bin/neo4j-admin database dump system --to-path=/full/path/to/dumps/
+----
+See xref:backup-restore/offline-backup.adoc[] for more information on the dump command.
+
+Use the `neo4j-admin database load` command to load the `system` database dump from `server01` to `server02` and `server03`.
+
+[source,shell, role="nocopy"]
+----
+./neo4j-admin database load --from-path=/full-path/data/dumps system
+----
+See xref:backup-restore/restore-dump.adoc[] for more information on the load command.
+
+Once the `system` database has been loaded on `server02` and `server03`, start all servers.
+The newly added servers should be in the `Free` state (`server02` and `server03`) and this can be verified using `SHOW SERVERS`.
+
+[source, cypher, role=noplay]
+----
+SHOW SERVERS;
+----
+
+[queryresult]
+----
++-----------------------------------------------------------------------------------------------------------+
+| name                                   | address         | state     | health      | hosting              |
++-----------------------------------------------------------------------------------------------------------+
+| "d6fbe54b-0c6a-4959-9bcb-dcbbe80262a4" | "server01:7687" | "Enabled" | "Available" | ["system", "neo4j"]  |
+| "e56b49ea-243f-11ed-861d-0242ac120002" | "server02:7687" | "Free"    | "Available" | ["system"]           |
+| "73e9a990-0a97-4a09-91e9-622bf0b239a4" | "server03:7687" | "Free"    | "Available" | ["system"]           |
++-----------------------------------------------------------------------------------------------------------+
+----
+
+On `server01` (the previously standalone server) verify that all user databases are still running using `SHOW DATABASES`.
+
+The last step is to enable the `Free` servers using `ENABLE SERVER` (see xref:clustering/servers.adoc[] for more information on server states).
+
+Once all servers are enabled, you can scale up user databases using xref:clustering/databases.adoc#alter-topology[`ALTER DATABASE`], if desired.
+
+====
+