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Storage Automation
Hierarchical Storage Management (HSM) is an archiving approach that migrates less active data off primary servers and moves it to less expensive storage, while keeping it available to users. George Symons, Legato's vice president of product management and development, defined HSM as "a way to use multiple storage environments for a conceptual single file system. Admin-istrators want to be able to set policy and move files from primary storage to a secondary or tertiary storage based on those policies."
It's no surprise that IT administrators need this sort of approach. Users are creating monster data files and IT is buying storage to match, but in fact most storage is seriously underutilized: common estimates for Windows systems are at 30%, and 40% for UNIX environments. Not only is storage hard to use to capacity, organizations also need the performance of disk-based systems. Caught in this cycle of under-provisioning and over-spending, companies need approaches that will keep files readily available for users, yet will help them stop spending money willy-nilly on expensive disk-- based storage systems.
HSM can help alleviate over-provisioning and performance problems by automatically migrating files along a hierarchy of storage devices from most expensive to least-- top tier, middle tier, and bottom tier. The top tier usually corresponds to fast, primary disk subsystems like RAID arrays. A secondary or middle tier can be less expensive disk, optical, or even fast tape, while tertiary storage is usually tape or optical. In this case, HSM is an addition to backup and recovery software-instead of making copies of data and storing them elsewhere, it moves the data from more expensive primary storage to secondary or tertiary storage. The move decisions are largely automated, set in advance according to the company's business rules and by the type of data.
HSM is different from backup....