EPiServer uses Microsoft SQL Server to store content and other information that is created in the system, all database editions including SQL Azure are supported. See the system requirements for details on which specific versions of SQL Server that are supported.
To make it possible to upgrade EPiServer CMS, you should never directly access the tables or stored procedures in the database, or create custom tables that interfer with the tables created by EPiServer CMS. It is recommended to always use the documented API instead, since no backwards compatibilty on the database level is guaranteed.
For availability and performance of the database, EPiServer CMS supports several SQL Server high-availability options, these include fail-over clustering and database mirroring. For instance, database mirroring is used to retrieve a “hot” standby database that operates in read-only mode, and all transactions are copied to the mirror, either synchronously or asynchronously. Instant fail-over can be configured using a “witness” server.
When running a SQL Server in production we recommend that a maintenance plan is created for the database including backup, checking database consistency and rebuilding indexes. Performance of the database will degrade over time if no maintenance plans is created, especially if indexes are never rebuilt the query speed will degrade as new content is added.
- Maintenance Plans on TechNet