Replica provides agents only for other Windows NT and NetWare servers, whereas the other two products provide agents for almost every server and desktop OS under the sun. ARCServeIT also works with most flavors of Unix. In the Event of Disaster You back up because you don't want to lose any data or productivity. If your server crashes, you want your data back right away. Fortunately, most products have some form of disaster recovery to keep downtime to a minimum.
Replica offers the simplest and fastest approach to disaster recovery.
Unlike ARCServeIT and Backup Exec, every version of Replica includes disaster recovery functionality. All you have to do is create a handful of disks and a full backup to a tape device. If your server dies, you can boot from the disaster recovery disks and have your server up and running within an hour. Both ARCServeIT and Backup Exec require you to reinstall a minimal portion of the OS before you can restore your data. Although this approach works, it is more complicated and requires more time.