Location Use During Checkpointing
A checkpoint (database backup) reads all the data from the Data location and writes it to the Checkpoint location. Checkpointing requires the most reading for the Data location, and is the only time Ingres writes to the Checkpoint location. Any updates during the checkpoint result in writes to the Dump location.
Dynamically compressing checkpoints is a common practice and decreases the disk space and writing bandwidth requirement to about one-tenth, while using more CPU.