What is HSM – Hierarchical Storage Management?

Answer 1

A data storage technique, which provides a automatic way of managing and distributing data between different storage layers (High cost and low cost media) in order to meet the users need for accessing data while minimizing the overall cost.

Answer 2

Also refered to today as Tiering. One needs to find out the " working data set". It is a percentage of a given work load where the reads and writes are higher as compared to older data. A rule of thumb is about 20% for a transcational Data Base.

By using "Tiering" your TCO for a storage solution whether primary or secondary can have a remarkable effect. Remember, not all your applications require sub-millisecond response at all times.

Example - If I arrive at a "WOrking Set" for all my work loads to be 1.5 TB, I will require only 2TB of useable drives with very high performance such as a NVMe, and provide for more economical drives such as SAS or NL-SAS ( high capacity) for my data that is outside of the " working data set".

Most storage solutions whether it is a 3-tier or a HCI architecture provides for "Tiering".

Note - HSM is an old terminology, however is still used by some vendors.