Storage virtualisation vendor DataCore has announced a free 30-day trial offer for its disk capacity-saving, thin provisioning technology. It now says thin provisioning is a green storage technology because it saves on empty disk space.

DataCore sells its SANmelody, and more capable SANsymphony storage area network (SAN) virtualisation products, which include a thin provisioning capability.

With a SAN, applications in attached servers are assigned a set amount of storage space on disk called a LUN, meaning logical unit number. This storage is accessed at the disk block level, not at the file level. The space is the amount the application will need over a long period of time as LUNs, once defined, cannot easily be modified. Such thin provisioning is not available to file-based, network-attached storage (NAS).

Thin provisioning, invented by DataCore in 2001, is a means of spoofing the application server's operating system, such that it believes a full LUN has been provided.

In fact, only a small proportion of the space has actually been allocated and, as it fills up with data, the space is gradually extended. Across a SAN, used by many servers and applications, this means a large amount of disk capacity is not needed at first and its purchase deferred.

In effect, customers have a month to set up a trial SANmelody storage area network and compare its disk allocation effectiveness to an existing SAN they operate. The trial offer package, to be downloaded onto a Windows PC server with up to 4TB of disk storage attached, does not include features such as Snapshot, Auto Failover and Asynchronous IP Mirroring which may be added to SANmelody.

Thin provisioning is provided by the SAN storage array vendor, such as Hitachi Data Systems. DataCore makes the point that it is independent of storage hardware vendors. It also asserts that its use reduces storage power and cooling energy costs and thus a customer's carbon footprint, because fewer physical disks and arrays are required.

George Teixeira, DataCore's CEO and president, said: "Being hardware-independent software also makes it easy for us to encourage people to explore the energy and money-saving, thin-provisioning benefits by making a 30-day trial available for download from our website. We thought, ‘since we are the only ones who can let everyone try this energy-saving technology, it’s something we ought to do.’”

But DataCore has been offering thin provisioning for some time and, it was suggested, is just adding a green spin to it. Teixeira responded: "When you see this much hype and smoke you know there has to be a fire somewhere. I won't deny that we (DataCore) jumped on the green computing bandwagon, why wouldn't we?

"It is a real flashpoint issue; IT managers are on the frontline impacted by server and storage sprawl and their rising energy and cooling costs. We've been touting thin provisioning savings for years. DataCore's thin storage can trim conventional fat storage from 10TB down to 4TB, that's a 60 percent savings - call it 'Green", call it what you like, but in the end it does make storage use more efficient and therefore it does save energy costs."