Tandberg Data has introduced a disk-based backup product with removable cartridges for small and medium businesses. It is cheaper and much faster than DAT-72, Travan or DLT tape drives.

The RDX QuikStor is a cartridge containing a ProStor 2.5-inch mobile hard drive with capacity of 40, 80 or 120GB. It can withstand a drop of 1 metre onto a concrete floor without damage and has an estimated 10-year life span.

This is inserted into a docking unit which comes in either a 3.5 or 5.25-inch form factor and is either an internal fit using serial ATA (SATA) 1, or an external unit using USB 2.0 connectors. It is SATA 2-compatible and the data transfer rate is 30MB/sec.

The RDX cartridge has a mean time between failures (MTBF) of 500,000 hours. The Travan MTBF figure is 40,000 hours and DAT-72's is 50,000 hours.

A Travan or DAT-72 tape cartridge can be used 50 - 100 times before it has to be replaced whereas the RDX cartridge has a 5,000 times load/unload cycle.

Travan drives transfer data at 3MB/sec, that's ten times slower than RDX. DAT-72 is 7.5 times slower than RDX. The Tandberg product is also faster than DLT version 4; the RDX backs up 80GB in under an hour. DLT 4 takes over 2 hours, while Travan will take over 7 hours.

RDX restores at disk access speed since there is no need to wait for a tape rewind time.

Another RDX advantage is that the docking unit is compatible with future cartridge drive capacities and recording technologies. It's anticipated that 400GB RDX cartridges will be available in a few years. There is a standard drive:docking unit interface that is independent of the drive's recording method and capacity. The docking unit has both forward and backwards compatibility unlike a tape drive which will generally have backwards-compatibility but not forward compatibility. An LTO3 drive will not read LTO4 tapes.

Iomega's basic REV removable hard disk (reviewed here) comes with 35GB capacity cartridges and a 25MB/sec I/O rate. A REV cartridge is just a disk platter and not the drive motor and read:write head. These are part of the REV drive unit into which the cartridge is inserted. An upgraded REV disk has a 70GB capacity and matches RDX with a 30MB/sec transfer rate.

Imation's Odyssey is a third removable hard drive technology. A fourth one, also from Imation, is Ulysses which has received a positive result from a trial by seismic data company Sercel.

With significant speed, price and media life advantages over tape it seems likely the small and medium business will steadily switch over to disk-to-removable disk backup and away from tape.

Tandberg's RDX QuikStor comes with Symantec Backup Exec QS. Prices for a docking unit and 40GB cartridge start at £162. A 40GB cartridge costs £65. Product is available now.