In complex systems, there may be a need to differentiate or triage different kinds of data for storage optimization. In these kinds of situations, auto-tiering can be an effective way of creating categories of storage for data.
Auto-tiering solutions can be applied to a logical unit number (LUN) or other kinds of file systems. IT experts sometimes talk about "sub LUN" as a specific type of auto-tiering.
As a specific kind of software-defined storage, auto-tiering is often useful for systems including solid-state drives and other types of storage networks that have different storage types. In many cases, auto-tiering provides for "hot" or frequently used data to be kept in certain more accessible drives or drives with certain properties, whereas "cold" data is kept in other kinds of drives for longer-term storage.