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About backups and media requirements

Back in the 80’s, the start of the micro-computer and home computing era, a backup could be done with floppy diskettes. PC Tools Backup would fit on one floppy and a complete system backup would fit on maybe ten or twenty. This was when the operating system was only a few hundred KB.

In the 90’s, the media moved to tape. First was the floppy interface tape drive that used tape cartridges with a capacity of 100 MB or so. A bit later came SCSI based tape drives that could handle 2 GB. Operating systems such as Windows 95 or OS/2 came on floppy sets. The CD ROM as a distribution and backup media became common in this decade as its 700 MB capacity was plenty for applications and software and sufficient for many backup needs. At the tail end of the 90’s, DVD’s became available. These were like super CD’s as they could hold more than five times as much data as a CD.

Floppies were cheap and didn’t require any extra hardware. Tapes were often an order of magnitude more expensive than floppies and required rather expensive tape drives. CD’s and DVD’s got back to fairly inexpensive media and their broad appeal brought the cost of the drives to handle them down to only moderately expensive.

Compression was a big deal. Most of the files subject to backup were text or simple memory representations that could be easily compressed down to somewhere between a half to a tenth of their original size in a backup. The files also tended to be rather small with sizes measured in kilobytes.

The pictorial presentation both on screen and in data is now the norm. In documents, fonts, illustrations, and layout descriptions mean that the word processing files are sized in megabytes rather than kilobytes. Images have increased in resolution and color depth. Audio and video both require significant data to represent anything other than a trivial segment.

One trend has been to compress data for storage in files. Word processing files used by Open Office, for example, contain the many components of the document compressed and collected as one file. A library of routines for software is similarly composed. Video and audio files often used sophisticated compression schemes that utilize a knowledge of human perception. What this means is that further compression to reduce backup media requirements doesn’t pay like it used to. Instead of being able to expect a backup file store to be less than half the size of the original files, you are lucky to get just a ten percent reduction in size and have to do an awful lot of computing to get even that.

The situation now is that an operating system needs several GB of backup media and many PC users have hundreds of GB of files that need to backed up. Even with DVD’s that gets to be a problem. Fortunately, hard drive storage technology has made it possible to provide the media space for modern backups at a reasonable cost. The interface technologies such as USB have also improved to make it easy to temporarily attach a storage device to a PC and copy over large amounts of data rather quickly.

Technology is also making other backup ideas possible. Broadband I’net is bringing up the idea of commercial backup servers so your data is backed up somewhere in the ‘cloud’ of internet space. Redundant drive array technology is reducing the risk of drive failures.

Now, what do you do when you don’t need that data anymore?

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