Here's a rare event: Blu-ray in a business archiving system. US archive product supplier PowerFile has upgraded its Active Archive Appliance to the A3 Enterprise Edition, using 50GB Blu-ray disks instead of DVDs as before.

This is not a traditional optical jukebox. Disks are stored in enclosures (libraries) and transferred to and from two drives by robotics. But the heart of the product is a so-called Archive engine, a 2U rack shelf server running the ArcOS file management software on a Xeon CPU. It has four 500GB serial ATA (SATA) drives on which it caches the most frequently accessed files stored on the Blu-ray disks. There can be up to eight individual library units, comprising two drives and 200 disks, plus the archive engine in a single 42U rack unit.

The library units are virtualised by ArcOS with disks being presented as volumes in a single logical storage space. This offers 70TB of capacity which is accessed over two gigabit Ethernet ports as a network-attached storage system (NAS) via NFS, CIFS and HTTP protocol. Expansion library units can increase capacity to 120TB.

The idea is to provide nearline storage access speed with tape-like capacity levels. Powerline says that the storage is highly power-efficient and delivers up to 500TB of storage per kilowatt of power. This, it claims, is less than a fifth of the power needed by a Copan MAID system which is an online, disk-based archive in which most disks are spun down.

The maximum throughput is 35MB/sec and the cache server disk capacity can be upgraded to 6TB. PowerFile claim that the A3's total cost of ownership is much less than that of equivalent capacity tape or disk-based archives. Unlike disks which can crash, or tape reels which need refreshing the write-once-read-many Blu-ray disks last for decades.

PowerFile is emphasising the A3's environmental credentials. Its CEO, Kirk Dunn, said: “Chief Information Officers at Fortune 500 organisations are managing under-utilized data centers due to power constraints and ever-expanding storage requirements, creating an immediate need for more energy efficient storage technologies.” In California the state electricity supplier, PG&E, will provide electricity rebates to PowerFile A3 customers, as it does for MAID products.

Equally keen to promote the product's greeness is media supplier Panasonic. Robin Sweeten, a Panasonic Industrial Company group manager, said: “This is a great example of ‘Blu’ actually contributing to a ‘green’ product.”

Competitor Plasmon offers offers UDO1 (0GB) and UDO2 (60GB) disks in its G-Series optical libraries. These do not employ a hard drive-based cache. However, it also offers an UDO Archive Appliance combining a UDO2 disk store with a RAID-protected hard drive cache which is presented as a NAS device. Capacities range from about one to 78TB. IT has recently announced a 50 percent year-on-year growth in UDO Archive Appliance sales

PowerFile positions its A3 product as being suited for mixed Windows, Unix and LInux environments needing volume management for tens or hundreds of terabytes of data. It is not best suited for Windows-only applications or ones where files larger than 20GB need archiving.

A PowerFile A3 Enterprise Edition base configuration with 10TB archive capacity and a 2TB cache is priced at $41,900 (about £21,000 at ordinary conversion rates).