What does storage virtualisation really mean?

Virtualisation has moved from being a shiny new technology concept to a sticky business that involves getting your hands dirty with some real technology and business problems. But while server virtualisation is now a well-known technique for saving money by increasing server CPU utilisation, storage virtualisation remains a hazy concept.

It means you can use the term how you like. Perhaps the best-known use of this technology is tape virtualisation, where your automated library of tapes takes care of exactly where your backups are stored, and just returns the data you want. Eventually. In theory.

On the other hand, virtualising rotating media is less well-known, mainly because it means different things to different people. Here at Storage network World in Frankfurt, the most – er – innovative, but perhaps instructive, use of the term so far was by analyst Tony Lock, who pointed out that every file system is a form of storage virtualisation.

How so? At heart, virtualisation is about hiding the underlying hardware from the software and management layers above, allowing the technology to take care of the intricate details of where an application is run, or data is stored. Given that definition, a file system qualifies.

So even when I was running a BBC Micro back in 1982, it included storage virtualisation. Who knew?

So when the vendor sidles up to you and whispers seductively about storage virtualisation, make sure you're both talking about the same thing. I'd be interested to learn what storage virtualisation means to you. No, really...