Taking advantage of the new 500-GB, 2.5-inch laptop drives recently released by Hitachi, Samsung, and Fujitsu, ProStor Systems is boosting the maximum capacity of its RDX removable disk cartridges, making them an even more viable alternative to tape for SMB backup and archival storage.While still about twice the cost of consumer USB hard drives on a per-gigabyte basis, RDX has the advantage of looking to backup and archive applications as removable, rather than fixed, storage. Most backup applications will span backup sets across multiple pieces of removable storage media, but won't span multiple fixed disks even if they're USB connected. SMB users outgrowing DAT can shift to RDX, gaining the fast, single-file restore advantages of backup to disk without changing their backup process.

ProStor's OEMs, Imation and Tandberg, have jumped right in, so any RDX users can buy the bigger cartridges through the channel of their choice.

Removable disk cartridges like RDX and Quantum's GoVault haven't really caught on, but the users I've talked with who've tried them love them. ProStor says it has 75,000 users.

From where I sit, the key to SMB backup is in the software, and RDX is frequently bundled with EMC's Retrospect, which does "keep it simple, stupid."