The database stores configuration and performance information. The three database deployment options are as follows:

• Use the embedded vPostgreSQL database on the VCSA or the bundled vPostgreSQL database if installing vCenter Server on Windows
• Install a full database server locally on the same server as the vCenter Server components
• Connect to a database hosted on a remote server

The embedded database included with the VCSA can support an inventory of up to 2,000 hosts and 35,000 virtual machines, which makes it a suitable option, even for very large deployments. The embedded vPostgreSQL on Windows, which can be deployed as a part of the vCenter Server Windows installation, is intended for smaller deployments of up to 20 hosts and 20 virtual machines. If a Windows vCenter Server is deployed using the embedded databases where the inventory is expecting growth beyond 20 hosts and 200 virtual machines, a different supported database option should be selected.

The Microsoft SQL Express Database is no longer supported in vCenter 6.x. When upgrading a vCenter 5.x server that was deployed using the embedded Microsoft SQL Express Database, the vCenter database will be migrated to the vPostgreSQL database as a part of the upgrade process.

Some reasons to use the embedded vPostgreSQL database when deploying a Windows vCenter Server are as follows:

• A small environment of fewer than 20 hosts and 200 virtual machines
• Easy installation and configuration
• Free! no need to license a separate database server software

Installing a full Microsoft SQL or Oracle database locally (on the same Windows server as the vCenter components) is supported, but this increases the amount of resources that are necessary for the vCenter Server. Additional resources may be required, depending on the size of the vCenter inventory. Hosting the database locally (on the same server) is fully supported, and this can provide faster access, since the access to the database does not rely on network resources.

A full installation of Microsoft SQL or Oracle can also be performed on a separate physical or virtual machine. The vCenter components access the databases hosted on the remote database server. The creation of the databases and the configuration of the vCenter components is the same as with a full database installation on the same server as vCenter. Accessing the databases requires network resources; because of this, network congestion or a network outage can affect the accessibility to the databases.

Some reasons to choose a remotely installed database are as follows:

• Leverage an existing database server that's already available in the environment
• For a separation of roles; database administrators are responsible for administering the database servers, while virtual administrators are responsible for administering the virtual environment
• High availability can be provided to the databases by using Microsoft or Oracle clustering
• It reduces the amount of resources that need to be allocated to the vCenter Server