Smallville High School had a file containing the names and marks of its students. While working with the diskette, the Principal accidentally deleted all the files. The results of the students could not be given on time.
The above mentioned problem would not have arisen if the Principal had additional copies of the same set of files.
Consider another situation. Suppose you open a file which contains a letter. To make modifications to it, you will open it, modify it and save the modified letter in the same file. If the power fails when you are saving the file, there is a chance that the data will get damaged. A damaged file is called a corrupted file in computer jargon. Now you will have to write the letter again, unless you had made a copy of the letter earlier. An additional copy of a file is called a backup.
Most computer users keep two or three copies of the same file. The original copy of data/software is called the master copy and the duplicates you make are called working copies. Most users use only the working copy so that the original is always available for emergencies. For example, the master copy will be useful if your hard disk crashes (a hard disk is said to have crashed if all the data and software stored in it cannot be accessed) and your working copy gets corrupted. Or, take the case when you are using your data after a long time. If the duplicate is corrupted, either due to bad storage or maintenance problems, you can always use the master.
Backing up is the process of archiving data and software. Since the amount of data to be backed up is usually very large (sometimes in excess of 500 MB), backups are typically taken on storage mediums like CD-ROM, cartridge tapes and M-0 disks. Most operating systems provide facility for backing up data and software.
Windows NT provides a utility for backing up and restoring files from tape drives. Windows NT Backup is a graphical tool for protecting data from accidental loss or hardware or media failures. NT Backup makes it easy to use a tape drive to backup and restore important files on the system.