RDX is a disk-based removable storage format developed by ProStor Systems Incorporated in 2004. In May 2011, Tandberg Data GmbH acquired the RDX business from ProStor Systems including intellectual property and key members of ProStor’s RDX engineering team. RDX is intended as a replacement of tape storage. RDX removable disk technology consists of portable disk cartridges and an RDX dock. RDX cartridges are shock-proof 2.5-inch Serial ATA hard disk drives and are advertised to sustain a 1 meter (39 in) drop onto a concrete floor and to offer an archival lifetime up to 30 years and transfer up to 650GB/hr. Hard disk cartridges capacities are 320 GB, 500 GB, 1 TB, 1.5 TB, 2 TB or 3 TB, solid-state cartridges capacities are 64 GB, doubling each to 512 GB per medium, or WORM media width 320 GB to 1 TB.
RDX is sometimes compared with Iomega REV, a formerly competing technology. REV places the read/write heads in the drive instead of inside the cartridge. It also allows an ordinary user to remove and replace the medium without special training. However, REV uses a removable-disk hard disk drive while RDX uses a fixed hard disk in a modular, replaceable package.