Monitor servers

To monitor the state of individual servers in a cluster, use the SHOW SERVERS command.

Listing Servers

Syntax:

SHOW SERVERS

Returns:

Name Type Description

name

String

The friendly name of the server, or its UUID if no name is set.

address

String

The address of the Bolt port for the server. May be null.

state

String

The state of the server in the topology.

health

String

The current availability of the server.

hosting

List<String>

Databases that this server is currently running.

Possible values of state

  • Free - server has been started, but not added to the cluster. It needs to be added with ENABLE SERVER.

  • Enabled - server is part of cluster and can have database allocated to it.

  • Cordoned - server may be hosting databases, but cannot have any more allocated to it.

  • Deallocating - server is in the process of removing its databases. This may take some time, because it does not stop its copy of a database, if in primary mode, until another server has fully started its copy, to preserve the requested number of primaries.

  • Deallocated - server has completed removing its databases.

  • Dropped - server has been removed from the cluster, but the process has not exited.

Possible values of health

  • Available - server has recently been in contact with the cluster member executing SHOW SERVERS.

  • Unavailable - server has not had successful network communication with the cluster for a while.

Unavailable does not necessarily mean the server is not running, just that there are network problems connecting to it.
Example 1. Listing servers in a cluster

When running SHOW SERVERS against a cluster, expect similar output to the following:

+------------------------------------------------------------------------------------------------------+
| name                                 | address        | state   | health    | hosting                |
+------------------------------------------------------------------------------------------------------+
|"f4ae1895-26f1-4b93-bd31-6f482be80d3d"|"localhost:7681"|"Enabled"|"Available"|["system","foo","neo4j"]|
|"ffa55a5b-2aca-45fc-be09-2a894067025c"|"localhost:7682"|"Enabled"|"Available"|["system","foo","neo4j"]|
|"server3"                             |"localhost:7683"|"Enabled"|"Available"|["system","neo4j"]      |
+------------------------------------------------------------------------------------------------------+

Listing more details of servers

If more details about the servers are needed, SHOW SERVERS can be appended with YIELD *.

Syntax:

SHOW SERVERS YIELD *

Returns:

Name Type Description

serverId

String

The UUID of the server

name

String

The friendly name of the server, or its UUID if no name is set.

address

String

The address of the Bolt port for the server. May be null.

httpAddress

String

The address of the HTTP port for the server. May be null.

httpsAddress

String

The address of the HTTPS port for the server. May be null.

state

String

The state of the server in the topology.

health

String

The current availability of the server.

hosting

List<String>

Databases that this server is currently running.

requestedHosting

List<String>

Databases that this server is supposed to be running. May be fewer databases if the server is in the process of safely stopping one, or more databases if the server is in the process of starting one up. Composite databases do not currently appear in this list, though they do appear in hosting for all servers.

tags

List<String>

Tags applied to this server. Used for routing policies.

allowedDatabases

List<String>

A list of the only databases that are allowed on this server. Empty means all are allowed.

deniedDatabases

List<String>

A list of databases that may not be hosted on this server. Empty means all are allowed.

modeConstraint

String

A limit on what modes (i.e. primary or secondary) a database can be in on this server.

version

String

The version of Neo4j this server is running.

Only one of allowedDatabases and deniedDatabases can be set as they are mutually exclusive.

Possible values of modeConstraint

  • NONE - any modes can be allocated to this server.

  • PRIMARY - only primary modes can be allocated to this server. These may be the target of writes for the database.

  • SECONDARY - only secondary modes can be allocated to this server. These will never write to the database, only read.

Example 2. Listing more details about servers in a cluster

When running SHOW SERVERS YIELD * in a cluster, expect similar output to the following:

+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| serverId                             | name                                 | address        | httpAddress    | httpsAddress | state   | health    | hosting                | requestedHosting       | tags | allowedDatabases| deniedDatabases| modeConstraint| version        |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|"f4ae1895-26f1-4b93-bd31-6f482be80d3d"|"f4ae1895-26f1-4b93-bd31-6f482be80d3d"|"localhost:7681"|"localhost:7471"|null          |"Enabled"|"Available"|["system","foo","neo4j"]|["system","foo","neo4j"]|[]    |[]               |[]              |"NONE"         |"5.0.0-SNAPSHOT"|
|"ffa55a5b-2aca-45fc-be09-2a894067025c"|"ffa55a5b-2aca-45fc-be09-2a894067025c"|"localhost:7682"|"localhost:7472"|null          |"Enabled"|"Available"|["system","foo","neo4j"]|["system","foo","neo4j"]|[]    |[]               |[]              |"NONE"         |"5.0.0-SNAPSHOT"|
|"72bd3d0f-c1d1-4d39-9da7-015f5656e40b"|"server3"                             |"localhost:7683"|"localhost:7473"|null          |"Enabled"|"Available"|["system","neo4j"]      |["system","neo4j"]      |[]    |[]               |[]              |"NONE"         |"5.0.0-SNAPSHOT"|
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+