A tenant database is a SQL Anywhere database that has been added to the cloud. Tenant databases contain data for the end users of the cloud.
A tenant database includes the database itself (read-write copy), as well as any read-only copies of the database.
For additional assurance of availability and performance, configure a tenant database to take part in a mirroring and/or scale-out configuration.
To maximize availability, set up a mirroring system for your tenant database. A mirroring system involves a primary database that is read-write, a mirror database that is a read-only copy of the primary, and an arbiter server that negotiates the primary and mirror roles. If the primary database fails, then the arbiter ensures that the mirror becomes the new primary and runs the read-write database. The arbiter does not maintain a copy of the database.
The documentation refers to the database running on the primary server as the primary database and the database running on the mirror server as the mirror database.
To maximize performance, set up a read-only scale-out system for your tenant database. A read-only scale-out system involves a primary database (also referred to as the root database) and at least one read-only scale-out database copy that is a read-only copy of the primary database. Read-only scale-out allows you to offload reporting or other operations that require read-only access to the database to read-only scale-out database copies.
To maximize both availability and performance, use mirroring with a tenant read-only scale-out system. When read-only scale-out is used with mirroring, the read-write database of the scale-out system consists of both the primary and mirror databases of the tenant mirroring system.