Overview of tiers
When not using Dynamic Tiering data is allocated to only one kind of data drive (typically an expensive high-speed data drive) without regard to the workload because the volumes are configured with only one kind of data drive. When using Dynamic Tiering, frequently access data is automatically allocated to the higher-speed HDT pool volumes and the lower speed drive to the volumes of low workload. This improves performance and reduces costs.
Dynamic Tiering places the host volume's data across multiple tiers of storage contained in a pool. There can be up to three tiers (high-, medium-, and low-speed layers) in a pool. Dynamic Tiering determines tier usage based on data access levels. It allocates the page with high I/O load to the upper tier, which contains a higher speed drive, and the page with low I/O load to the lower tier, which contains a lower speed drive.
The following figure illustrates the basic tier concept.
