Iomega offers a $209 single-drive shared storage device similar to that offered by Buffalo, but I opted to test the $439.95 dual-drive configuration, which allows mirroring on two internal 250GB disk drives for disaster recovery. Both drives are SATA with 3Gbit/sec throughput. That's a very nice feature to have, but it also adds about $200 to the cost while cutting available storage space by half.

Iomega's 500GB StorCenter is a shorter (just under 5 in. tall), wider (just over 3 in.), more compact unit that's less likely to get knocked over than other models I tested. The single-disk, 250GB model can't be mirrored, but a four-disk, 1TB unit supports a fault-tolerant, RAID 5 configuration. The StorCenter was the only unit I tested that uses a parallel ATA disk interface rather than the newer, serial ATA standard, which offers faster transfer rates. In daily use, however, the unit was not noticeably slower than the other units.

The 500GB model can be configured to stripe data across the two disks (RAID 0), ostensibly to increase performance. RAID 0 is the default. Alternately, the system can make both drives appear as a single volume, filling up first one disk, then the other. Performance-wise, most users probably won't notice a difference either way. But if pieces of every file are stored on both drives, all files could become corrupted when one drive fails in a RAID 0 configuration. By contrast, with drive spanning only the files stored on the failed drive would be lost. Given that, my preference would be to opt for drive spanning or mirroring. I chose the latter.

Setting up mirroring requires reformatting the drive, a process that takes a few hours. Once set up, mirroring was transparent and worked seamlessly.