When storage costs keep getting higher for an organization, there isn’t much a storage admin could do to manage data storage across various storage devices and media. There has to be some prioritization of data stored and it should be decided where to storage what data. If it’s critical data requiring frequent access, then it’d need a high performance and expensive storage array, while data of low importance and backup might be stored in slower and cheaper disks. This process of moving storage between different storage types is known as storage tiering.
Examples of Storage Tiering
Mission-critical & recently accessed files
Stored on expensive and high-quality media such as double-parity RAIDs
Seldom-used, classified files, backup
Stored on less expensive media in conventional SAN
Event-driven, rarely used, unclassified files
Stored on recordable compact discs or tapes
These are just some examples to understand the concept. Actual storage tiers may vary and depend on your organizational storage access, requirement and hardware availability.
Automated Storage Tiering
To overcome the manual efforts involved in moving storage across different tiers, storage vendors came up with the concept of automated storage tiering – which is a storage software management feature that dynamically moves information between different disk types and RAID levels to meet space, performance and cost requirements. 
Storage admins can decide to dynamically move storage blocks or LUNs across different storage types for different reasons.
- Progression is where highs accessed data and critical files are moved from cheaper and low performance storage media to high performance SAS or SSDs.
- Demotion is where infrequently used data can be automatically moved to slower, less-expensive SATA storage.
The movement of LUNs across storage tiers is managed by auto-tiering algorithms programmed in the storage management software. Some software use heat-map approaches to determine storage access and usage over a particular time period to dynamically move storage from one tier to another. There are many leading vendors in the market that support this functionality. Some of those are:
- Dell® Compellent – Data Progression
- EMC® – Fully Automated Storage Tiering (FAST)
- HP® 3PAR – Adaptive Optimization
- IBM® – Easy Tier
- Hitachi® – Data Systems Dynamic Tiering
Some vendors claim that it is possible to perform real-time automated-tiering on storage blocks in small sizes – ranging in KBs to a few MBs.
Third-party storage management software will also help provide information on disk storage for LUNs based on storage tier, tiering policy applied and whether auto-tiering is enabled or not. You can check out SolarWinds Storage Manager ver 5.7 which will extend support for EMC FAST VP implementation on VMAX/Symmetrix and VNX arrays. Learn more about Beta trial of Storage Manager ver 5.7 >>