Dell Compellent Series 40 - Manual (Page 230)

222 Storage Center 5.5 System Manager User Guide
System Management
Figure 184. Storage Consumption Trends
Data Progression Pressure Reports
By default, Storage Center using Data Progression gradually migrates data down from
high-end drives to be stored on lower-end drives. If a disk class is full, Storage Center writes
data to the next lower class. Using Storage Profiles, you can create volumes that reside
only on one disk class. For example, a volume that contains only Replays might be stored
on a lower disk tier.