Backup So Easy Even Your Users Can Do It: Page 2 of 20

This can be a challenge, especially when taking a local-storage approach that may involve connecting a device to the computer or inserting media and initiating a backup that may prohibit other work. The task can be shortened by an incremental or differential backup, which writes only files that have changed since the last backup, but for the most part a local storage backup remains user initiated.

Online backup, whether to a service provider or to your server, can occur whenever the user connects to the Internet, either through user initiation or by schedule. The level of complexity varies substantially between software packages and services, but all remote-backup packages minimize backup time through compressed incremental backups. In addition, many online clients are designed for low processor utilization to allow background execution while other work is in progress.

The time required for a remote backup depends on how extensively the data has changed since the last backup, the connection speed and the degree of data compression. The initial backup will take the longest--possibly hours depending on data volume, even when attached directly to the local network. Estimates of typical online backups range from two to 10 minutes on a broadband connection, but may take 10 times longer over a dial-up connection. Fortunately for dial-up users, all the products we examined are designed to handle and resume interrupted transmissions, so a backup routine may span more than one connection period.

Data Security: Mum's the Word

Security for the mobile backup can be addressed at several levels. Online, the first level is at login, using a secure authentication mechanism with passwords or digital certificates. The second is during transmission, using data encryption in the event you need to send over an unsecured connection. The third level of security encrypts data at the server or storage level (see "DB Confidential,").