| Computers perform an ever-more useful role within businesses. They are entrusted with increasingly complex jobs and are usually expected to be 100 percent reliable. Unfortunately, there is always something that can fail, usually at the wrong moment, which makes it imperative that regular backups are taken to ensure that you are able to deal with all types of problems. A backup is a copy of the data that is stored on the computers hard disk(s) that can be used to recreate that data should it become lost or corrupt. Problems requiring restoration from backup range from a user inadvertently removing the wrong file to a major hardware failure causing loss or corruption of whole disks worth of data. Backing up a system is not simply a matter of copying all the files to tape. There are a great many factors to take into account, which means each server is likely to require its own backup strategy. Once a backup strategy is defined, it should be fully tested, which should include the recovery of data from the backup, as well as the actual backup process. It is all very well to take a full system backup every night, but if you haven't tested how you will use it to rebuild the system, you will find that the hours following an emergency are not the best time to do it. | 
