Mozy, the online backup service, is testing out a bit of technology offered by rival DropBox: file synchronization.

The company started telling customers today that it's begun closed beta testing of the sync feature, which will let files stored on one machine automatically be replicated on another. It's a big advancement over Mozy's bread-and-butter of file backup, transforming the service into something people actively use rather than run passively in the background. It also dovetails with the multicomputer subscription plans Mozy introduced in January at the same time it announced it's ditching unlimited-data backup.

Also taking a page from Dropbox, Mozy announced mobile apps for Android, iPhone, and iPad that let people access their archived files. Again, this makes an archive more actively useful.