Many organizations use tape to back up data nightly. Tape is fairly inexpensive and low-tech, but managing and administering tape, backing up to tape and restoring files from it can be time consuming, unreliable and complex. Disk has always been an easier, more reliable alternative, but until recently its high acquisition cost has made it untouchable for many organizations. Fortunately, new disk and data reduction technologies have recently converged to make disk-based backup available at about the same price of tape backup systems. This white paper examines the pros and cons of both technologies and will present a cost analysis of ExaGrid's disk-based backup system with data de-duplication and compression vs. tape and standard SATA disk.