Network Appliance has virtualised its storage. Its microkernel appliance operating system, Data ONTAP, has had virtualisation added in its latest version, 7G.

The company said that all the disks in virtualised NetApp appliances have their blocks added to a single dynamic pool from which volumes are created for servers. These can be file-based (NAS) or block-based (SAN). Their logical size can be adjusted dynamically and physical storage is only used up as data is written to the so-called FlexVols.

NetApp competitors, with the exception of EMC, have virtualised their storage for some time. HDS has recently announced its TagmaStore. IBM has its Storage Tank project with the SAN Volume Controller. HP has its EVA meaning Enterprise Virtual Array and has more storage virtualisation on its roadmap via smart cells in storage grids. EMC recently demonstrated prototype virtualisation.

Now NetApp has gone public on its product and plans. Keith Brown, NetApp technology director, said, "Customers get two or three times the storage utilisation of other virtualisation systems." This saves cost. The data is also better protected as NretApp's RAID DP scheme protects data better than mirroring whilst requiring fewer protection disks. Mirroring can produce data loss if disk pairs fail in the source and mirror set or if a source disk fails and its mirror pair suffers bad block syndrome. RAID DP protects against this.

Data ONTAP 7G is an upgrade and existing NetApp customers, with, for example, FAS and NearStore systems, can upgrade to it and have their storage virtualised. NetApp's GFiler is an appliance that uses third party disk arrays to actually store the data. It too can be updated to Data ONTAP 7G, meaning that arrays from IBM, HDS, Sun and HP, can also be virtualised the NetApp way.

NetApp is number four in storage revenue terms, after EMC, HP and IBM. But its measure excludes tape systems and counts only networked disk storage. Brown says the company has enjoyed 40 percent year-on-year growth and is earning around $1.5 billion per annum.

NetApp says its automated storage provisioning is lighter in administrator man-hour terms than competing products.

The 'G' in 7G means that it is a step in the road to a storage grid. Brown says NetApp will use technology from its Spinnaker acquisition to virtualise storage from separate NetApp storage systems and provide a single logical namespace. Computers anywhere on a grid will be able to see storage, NAS or SAN, anywhere on the grid. Exagrid, with its clustered NAS product, offers this capability already for NAS users.