Database storage

• Local storage is the directory directly accessible to the OLAP Service worker by way of the operating system. It is usually a folder on a hard drive of the machine hosting the OLAP Service. The corresponding directory exists only during the run time of the database.
• Central storage is persistent storage, either on Amazon Simple Storage Service (Amazon S3) or any storage available to the operating system. The central storage type is also used for the persistent storage of backups.

Regardless of the deployment target such as cloud or on-premises, an OLAP database is persisted on central storage. When a database is started, the necessary files are downloaded from central database storage to local storage.

The Cube Save and Dimension Save functions flush the in-memory state of the targeted object to local storage. For being fully persisted, the changes must be transferred back to the central database storage. That is achieved by running the Database SaveKernel function to save the database. You can also use EPM Administration to save the database immediately or to schedule regular saves.

When a database is stopped, it is saved and the local storage directory is deleted.

In on-premises installations, the local and central storage directories can be viewed in the service-specific OLAP settings of the Services dashboard in EPM Administration. They can be changed in the Directories tab in Service Expert.