Iomega is releasing this week a new all-around backup solution: It uses hard drive technology, but is packaged in removable cartridges so you can buy one drive yet swap media.

The Iomega Rev 35GB/90GB drive is available in several configurations. The external USB drive lists for $400 (just over £200); the internal ATAPI drive goes for $380. Both come with a single, 35GB cartridge. Individual disks will cost $60, or $200 for a four-pack (around £30 and £100, respectively).

The product has a capacity of 35GB. The "90GB" in its name refers to the theoretical capacity of a compressed backup, according to Iomega representatives. But how much a file can be compressed depends on the file format, since many space-hogging formats, including .jpg and .mp3, barely compress at all.

Conventional hard drives are hermetically sealed; dust can't get in to mess up the works. That's why they're fast, reliable, and have huge capacities. But it's also why you can't take the disk platters out of one drive and put it in another.

Iomega says it has designed the Rev drive to stay clean without sacrificing the capability to remove it from its box. The shutter on the drive and the shutter on the cartridge open in tandem, so the sealed environments of the read/write heads remain clean inside the drive. They also get cleaned automatically. An air filtration system emulates the clean environment of a conventional hard drive.

The drive uses the same error correction system -- UDF 1.02 -- as optical drives, though it's an older version of UDF. Iomega is using this version because a variety of operating systems contain native UDF 1.02 readers, which helps make the Rev highly compatible, say company representatives. You can plug and play a Rev device somewhere that doesn't have a UDF reader, and you'd still be able to read the data, but not write to it.

According to Iomega, the result is an extremely reliable drive, with an error rate that representatives say is "three orders of magnitude" better than standard hard drives. And although the Rev is not as fast as a hard drive, Iomega reports an average transfer rate of about 20 megabytes per second. That's in the neighborhood of the fastest DVD drives, and much faster than tape drives.

And tape is the technology Iomega wants to replace. The Rev is designed for users who now rely on or are considering tape as their backup medium. Iomega says the Rev handles the job because it, too, is a back-up medium with a capacity larger than a DVD, and is more reliably portable than USB hard drives. Primary targets for the product are small businesses, home offices, and vertical markets.

In theory, a removable media solution is more economical than an external hard drive -- at least if you believe in keeping more than one backup (as advised). After all, the expensive, precision machinery is in the drive, not the disk, and with removable media you only have to buy one drive.

But unless Iomega offers some very significant discounts, the Rev drive is the larger investment. One Rev drive and three cartridges will cost about $500 (£250). You can buy three external USB hard drives for about $300 (£150).

Rev Product Manager Lake Price notes that the drive has other advantages over standard hard drives. Its smaller cartridge size makes it easier to carry. Also, your data is safer when the motors and the data aren't in one sealed box.

"Drop (a Rev cartridge) on the floor and you're not going to break any components," Price says.

Iomega also sees the Rev as an archival medium, especially for vertical markets that must store huge amounts of data, such as video production and software development. The company estimates the cartridges will hold their data for more than 30 years. Of course, with time and technological progress come new standards; the new drives of three decades hence may not be able to read those cartridges.

The drive comes bundled with a new, Rev-specific Pro version of Iomega's Automatic Backup program. The program's estimated 2.6:1 compression ratio, new to this version, is what puts that "90GB" into the drive's name. Another new software feature is AES encryption. Also bundled with the drive is a special version of Norton Ghost, a disk-imaging backup application.

Iomega hopes to see Rev drives come installed in server and business desktop PCs in the near future. Hewlett-Packard and Dell are among the manufacturers planning to offer it as a stand-alone product. Other future plans include FireWire, SCSI, and SATA models, an emergency recovery program, and higher-capacity versions of the drive.