Sometimes referred to as a streamer, the tape backup is a form of data storage that is used to create a copy of the data stored in a system at a specific point in time. The data are copied onto a reel of magnetic tape, and can be permanently archived for future reference. Before the advent of the compact data disks, using a backup of this type was common for many businesses that relied heavily on computer databases. Even today, the dependability of the magnetic tape and the relatively low cost make using a tape backup an attractive option.
The actual back-up process is not unlike that of copying data onto a remote server or a CDR. Software is used to initiate the process and monitor its progress. In general, the magnetic tape backup can read data from a hard drive with speed equal to other data storage options and copy the data to the tape with relative ease. When finished, the tape can be stored and archived, effectively creating a snapshot of all the data within a system as of a specific date and time.
While backing up data on a disk is fine for creating a copy of current information in the system, the process of accessing the stored data is somewhat different than with a backup using magnetic tape. The disk drive allows for what is known as random access. Essentially, this means it is possible to search through and skip around in the saved data. By contrast, most tape backup systems allow for sequential access only. The data are accessed at the beginning of the captured data and then moved through in the order it was recorded.
The equipment used in a tape backup has been enhanced over the years. Systems used with large mainframes decades ago often had to pause and sometimes rewind slightly in order to accurately capture data. This was because the magnetic tape running onto spools would not always move at a consistent rate of speed. By the 1980s, buffering equipment was added to minimize the potential for lag and decrease this stop-rewind-start activity.
In recent years, the ability to employ more than one speed level to the tape backup process has been added to the recording systems. This makes it possible to adjust the reading and capturing of the data onto the magnetic tape so that the process advances smoothly. Along with the buffers, this has helped to further minimize the incidents of stopping and starting due to incidences of lag.
It is not unusual for many corporations to utilize a tape backup as well as encourage the use of other data storage options. For example, a company may copy data onto a remote server, providing instant access in the event of a failure of the primary server. A tape backup is still conducted daily, usually at night, as a means of capturing a snapshot of how data looked at a given point in time. A strategy of this type results in a great deal of security for the company, making it virtually impossible for data to be permanently lost.