AST (Automated Storage Tiering)
Automated storage tiering (AST) is a storage software management feature that dynamically moves information between different disk types and RAID levels to meet space, performance and cost requirements. The movement of data takes place in an automated way with the help of a software or embedded firmware and is assigned to the related media according to performance and capacity requirements. Advanced implementations include setting policies for data movement by storage administrators. For example, a data storage administrator can assign infrequently used data to slower, less-expensive SATA storage but allow it to be automatically moved to higher-performing SAS or solid-state drives (SSDs) as it becomes more active (and vice versa).