A backup simply means an additional copy of your data, nothing else. The fact that the storage medium is disk means that access and speed are improved over other media such as tape. If you have ever waited for a backup tape to find the point in the tape that you wish to recover, you know what time savings disk backup provides. Once the backup copy is complete, however, it is just stored data. One still needs to be able to manipulate and process this data with hardware, applications, etc. For example, removable storage media can hold backup data, but it is worthless unless it can be connected to the processing hardware.
A disaster recovery appliance usually includes the necessary infrastructure to process data quickly. The hardware and applications that process the data are available and ready to process. This architecture tries to eliminate the need to build an environment while in a recovery scenario, as this can be time-consuming and can result in errors. Disaster recovery appliances are often found in virtual environments today.
This was first published in September 2010