Circular storage

Circular storage is used for the main historical data storage. The Storage subsystem creates history blocks of the configured default duration when the data falling into the corresponding time interval needs to be written to disk.

The circular storage location is used to write data in a "circular buffer" fashion. When the free disk space on the disk containing the circular storage location drops below a minimum threshold or when the data is of a specified age, the history block in that storage location is moved to the alternate storage location, and new history blocks get created when necessary. You can also limit the size of the circular storage location. When the contents of the circular storage location reach or exceed this limit, the oldest data will be moved to the alternate storage location. If no alternate storage location is configured, the data is deleted instead of being moved. For more information, see Automatic deletion of history blocks.

It is the responsibility of the system administrator to monitor disk space and back up history blocks to a safe location on a periodic basis.