Data Domain has produced a disk array that can hold 20 times more backup data than its physical capacity - the storage equivalent of Doctor Who's tardis.

The DDX and its new DD560 controller offers up to 15 petabytes of capacity and a throughput of up to 6.4TB per hour where the actual capacity is 750TB with a 32GB per hour throughput. The extra space is found by "de-duping" the data using software running in the array's 64-bit Intel controllers which shrinks it at wire speed to a twentieth of its size.

An initial backup identifies data chunks that are identical and only stores one instance of them together with storage metadata which specifies when and where in the incoming file the data chunks should be used to rebuild it when it is restored. Data Domain calls its de-duping Global Compression technology.

In subsequent backups only new chunks of data are stored and the amount of new data saved over time drops to a twentieth or less of the incoming data, depending upon the backup data type. The 20:1 ratio applies to general business backup data types such as databases and unstructured data.

Data Domain claims its cost per gigabyte is far lower than competitors' virtual libraries, citing 50 cents per GB compared to $1.67 per GB for HP's VLS6870 (Sepaton) with compressed data. The DDX also has lower power requirements when measured on how much non-de-duped data is stored. Data Domain says it requires 1.3 to 2.8W per TB compared to 53W per TB for an EMC Clariion DL740 with compressed data.

The DDX comes in 4, 8, and 16 controller configurations. Data is protected using dual disk parity RAID 6 and also continuous recovery verification using the array controllers. The DDX supports up to 320 remote sites and can act as a consolidated backup centre for them.

It is intended for organisations with at least 20TB of application data. Integrated or third-party drive arrays can be used. Pricing depends upon controller model and array configuration. It is available now starting from $95 per TB for 100TB of usable storage, equating to 5TB of physical disk storage.