vRealize Automation requires the appliance database for system operation. You can manage the appliance database through the vRealize Appliance Virtual Appliance Management Interface.

Note:

This information applies only to deployments that use an embedded appliance database. It does not apply to deployments that use an external Postgres database.

You can configure the database as a single node system or with multiple nodes to facilitate high availability through failover. The appliance database is set up initially when you install vRealize Automation, and it requires no maintenance unless a machine configuration changes or, in the case of a clustered configuration, you need to promote a different node to be the master.

Note:

The database clustered configuration is set up automatically when you join a virtual appliance to the cluster using the Join cluster operation. Importantly, however, the database cluster is not directly dependent upon the virtual appliance cluster. For instance, a virtual machine joined to a cluster can operate normally even if the embedded appliance database is not started or has failed.

A clustered configuration contains one master node and one or more replica nodes. The master node is the vRealize Automation appliance node with the master database that supports system functionality. Replica nodes contain copies of the database that can be pulled into service if the master node fails.

Several high availability appliance database options exist. Choosing the replication mode is the most important database configuration option. The replication mode determines how your vRealize Automation deployment maintains data integrity and, for high availability configurations, how it fails over should the master or primary node fail. There are two available replication modes: synchronous and asynchronous.

Both replication modes support database failover, though each has advantages and disadvantages. Note that to support high availability database failover, asynchronous mode requires at least two nodes, while synchronous mode requires at least three nodes.

Replication Mode

Advantages

Disadvantages

Synchronous

Minimizes chance of data loss.

  • Might affect system performance .

  • Requires at least three nodes.

Asynchronous

  • Requires only two nodes.

  • Affects system performance less than synchronous mode.

Not as robust as synchronous mode in preventing data loss.

vRealize Automation supports both modes, but operates in asynchronous mode by default and provides high availability only if there are at least two appliance database nodes. The Database tab on the Virtual Appliance Management Interface enables you to switch synchronization modes and to add database nodes as needed.

If you start with one node in a non-high-availability configuration, you can add nodes later as required to enhance high availability. If you have the appropriate hardware and require maximum protection against data loss, consider configuring your deployment to operate in synchronous mode.