Once installed, the Mirra Sync client software starts by asking you to choose the files you want to back up and can maintain up to eight revisions of each file. Backups are slowly copied directly to the Mirra Sync and are not compressed or encrypted. You can and should password protect backups because if you don't, other users on your network will be able to see and possibly delete your backups.

Once you've created your backup sets, you can choose to enable Web access for those backups and then share any folder within a backup set. Data can be shared by choosing other users on your network from a list or over the Web by entering the e-mail addresses of remote users you want to invite to access your data. Remote users then register and obtain a password at the Mirra.com Web site, which redirects them to the shared files on your Mirra Sync device. By default, users can download image files but don't have write access to shared folders. For reasons discussed below, I recommend keeping it that way.

Nuts and bolts

Mirra.com overcomes some technical challenges that you would encounter in trying to publish content directly to the Web. It maintains a link to your local Mirra Sync's IP address, and it redirects users to the resources shared on that device. That's important because your broadband modem or router assigns a dynamic IP address to the Mira Sync and other clients on your local network that is not visible from the public Internet. By using Seagate's free Domain Name System redirect service, the Mirra Sync gets around that problem -- so long as your firewall leaves UDP Port 19430 and TCP Ports 80 and 443 open. (This might explain why it would not work on my Computerworld-issued laptop).

Mirra Sync is not a traditional shared network storage device but replicates, or synchronizes, file changes between systems. That's an important difference to understand. While NAS devices use file-sharing protocols such as the Common Internet File System (CIFS) to facilitate file sharing and allow file and record locking to prevent people from overwriting changes to one anothers' files, the Mirra Sync simply uses replication to keep files up to date. When a file is changed in one location, versions in other locations are automatically overwritten with the new version.