Devspace 

The term "devspace" denotes a physical disk or part of a physical disk. This can be a raw device (UNIX only) or a file.

The drives used should have identical performance parameters (specifically access speeds) to ensure even distribution of data on the devspaces.

The database system has system devspaces, data devspaces and log devspaces.

Each database instance has one system devspace and one or more log and data devspaces. You configure the maximum numbers of data and log devspaces that are possible when installing the database instance.

If necessary, you can add data or log devspaces to a database instance while the database is running. Paths for data and log devspaces can be changed.