Conventional wisdom, as usual, needs updating. The back-up medium of choice used to be tape, end of question. Now backups are done using disks, offsite storage and removable hard disk cartridges. While Iomega's REV drive had the market to itself for some time, now Quantum has jumped in with its new GoVault product line.It's fascinating to see vendors stake out positions. Iomega's REV drive came out first, and I talked about them last October. Quantum arrives later but ups the ante with GoVault cartridges in three different capacities (40G bytes, 80G bytes, 120G bytes) that fit into a drive installed into a server. Iomega has internal drives, but its external units are far more popular.Both companies use 2.5 inch hard drives parts developed for laptops, reducing costs since they can buy parts rather than designing and making them. As laptop drives increase in capacity, so can these removable drives.Quantum's drives are taller than the REV drives, using the extra height to stack platters for higher capacities. I'm sure the REV drive folks are working to increase capacities as well, but they haven't announced anything yet. The REV drive cartridges are flatter but wider and may make it tough to bump up the capacity as quickly as the GoVault drive cartridges.The Quantum internal drives are cheaper than Iomega's external and internal drives ($299 estimated street price vs. $350 for Iomega's IDE interface internal drive), but the company\u2019s cartridges are more expensive. REV cartridges range between $50 and $65 depending on volume, and Quantum promises a street price of around $120 for its 40G byte drive. Get more than one cartridge and the start-up pricing between the two becomes a wash. Quantum's 80G byte cartridges will be around $200, and its 120G byte cartridges will be around $300, so they will remain more expensive per gigabyte than REV cartridges ($50 each retail when bought in 4-packs).Another difference? Iomega uses IDE, SCSI, and SATA for its internal drive connections (along with USB, FireWire, and SCSI for external drives), but Quantum offers only SATA internal drives with its server-based units. Any server built in the last two years should have a SATA connection, whereas millions of existing PCs and servers don't have that option. Quantum plans to work primarily through server manufacturers and smaller vendors who build their own servers from parts. For those people, a SATA connection makes sense (it's faster than IDE and some SCSI connectors) and is easily available.A benefit of Quantum\u2019s disk being internal to the server is most existing back-up software will treat the GoVault drive like any other disk drive. The Quantum smart drive holding the cartridges has it's own intelligence, including a SATA connector to talk to the SATA connector on the server motherboard. Users will be able to address the GoVault like any attached drive using Windows network sharing drive letters, similar to how you address an Iomega drive. Quantum also throws in Yosemite back-up software.Kudos to Quantum for developing another removable hard disk cartridge system and bumping up the capacities. Kudos to Iomega for establishing the market and pricing its cartridges lower than Quantum feels comfortable selling its wares.If dollars per storage gigabyte matter, stick with tape. Quantum leads the market in several tape technologies, and is working on a new 1.6T byte tape cartridge. That unit will provide a 6 cent\u00a0per gigabyte price of storage, far lower than disk cartridges from Iomega or Quantum (but the tape drive unit costs more).If better back-up and restore speed matter, try one of these hard disk cartridge system. Both act like a hard drive, allowing faster file transfer and the ability to search the drive for files randomly rather than following the tape one data block at a time from the beginning until the end. Tapes tend to be more susceptible to damage from the environment (heat, for instance), and sometimes don\u2019t work reliably when you need them the most.A disk cartridge back-up system from Quantum or Iomega will cost under $700 for the unit, software, and at least three cartridges. I say three for a reason, since you need one rotated offsite all the time for disaster recovery. Your hard disk system will be faster and more reliable than your old tape drive. Even better, now you have a choice of brands and cartridge capacities.