Anyone who has more than one computer may have to synchronize their files to make them the same on both or all computers.

For example, I have a tower system in my home office, a tower in my university office and a portable computer. All are supposed to have exactly the same files. In addition to the simple matter of convenience, synchronizing the computers provides excellent backup. In addition to my daily incremental backups (that is, backups of all files that have changed since the previous incremental backup) and my monthly full backups, the inactive synchronized computers serve as daily full backups of the currently active computer.

For many years, I have been connecting my home-office tower to my portable using Laplink software and a special USB cable. The Laplink Gold product unfailingly checks files on the source and target machines, and allows you to choose how to transfer changes:

* Clone the target machine using the source machine as the standard (i.e., make the target identical to the source)

* Add all new files from the source to the target without deleting any files on the target

* Add all new files from either machine to the other without deleting files

One of the best features of Laplink is that it scans the content of files on both systems to identify blocks that differ, rather than simply transferring entire files. So, a 200M-byte file with only a few changes may take but a few instants to synchronize across the cable, resulting in effective transfer speeds in the hundreds of megabytes per second.

Laplink Gold Version 12 also provides connectivity through the Internet if the computers are physically distant. For example, it is possible to synchronize my two tower systems directly to each other without having to synch the portable from the home-office system and then synch the university-office system from the portable.

Another useful feature is the Laplink Remote Desktop. This function allows you to work on a remote computer using a desktop running on the local computer, effectively functioning as a LAN or WAN connection among your own computers. File transfers for individual files to and from the remote system are available much like FTP.

The product allows you to define scripts for automated checking of specific sets of folders, with user verification of conflicts (e.g., if both copies of a particular file have changed on each machine since the last synchronization, thus raising the question of which one should take precedence).

M. E. Kabay, PhD, CISSP-ISSMP, is Program Director of the Master of Science in Information Assurance program at Norwich University.