-written by Pat Kelsey, Dataram Storage Blog Team Member
For about as long as there has been storage, there have been different storage technologies on the scene at any given time, distinguished from one another primarily by price, performance, and reliability. Traditionally, integrating these multiple tiers of storage into the SAN was something seen mainly in the large enterprise, where the operational scale and performance requirements justified the attendant cost and complexity.
In the SMB/SME environment, the combination of growing active datasets and the attractive price/performance point of flash memory motivates adding a third tier to the typical two-tier storage architecture (of rotating media fronted by volatile and non-volatile cache RAM on the array controller). With new memory technologies currently a very active area of research and development, it’s easy to imagine a fourth tier reaching commercialization in the next 5-10 years.
Integrating multiple tiers into a storage appliance can offer much higher performance and greater management simplicity than dealing with separate technological islands in the SAN (or forgoing the additional tiers completely). The key is to strike the right balance between automated data management and application-specific migration policies – some users may be served well-enough by generic tiering algorithms, but others (those using filesystems with separable metadata and those dealing with database transaction logs come to mind) will want to pin certain data to specific tiers in the hierarchy to obtain maximum performance.