Reliability of data storage media



The purpose of this page is to present the different computer data storage media types and investigate their long term reliability, data preserving and immunity to failures due to physical factors. This page ignores issues related to data capacity and media obsolesce and it does not try to compare media based on these properties.

I have decided to write this article after a thought I had of what type of data storage media should I use for my simple, failure immune 4-bit digital computer made out of common TTL chips. I will borrow many information from Wikipedia as long as other websites and papers, so please have this in mind when you read this article, as I am not able to present here the exact sources I have taken the material from.

Types of data storage media

There are four common basic types of computer data storage media: Magnetic, optical, semiconductor and paper.

Magnetic consist of a variety of magnetic media and containers including a range of magnetic tapes such as reels, cartridges, cassettes and disks. They all utilize the magnetic properties of metallic materials suspended in a non-magnetic mixture on a sub-strate. The method of construction and storing the data, point to potential weaknesses of magnetic media.


Optical storage media use laser light to read from a data layer. A number of different types such as CD-ROM (Compact Disc - Read Only Memory), CD-R (Compact Disc - Recordable), and DVD-ROM (Digital Versatile Disc - Read Only Memory) exist.

In CD-ROM the data layer consists of a series of pits in a metallic coating over a plastic disk. A clear acrylic coating is applied to the metallic layer to protect it from light scratches and corrosion. CD-R employs a dye layer which is light sensitive as the data layer.

Magneto-optical disc storage is a combination of optical and magnetic technologies and it uses the magnetic state on a ferromagnetic surface to store information. The information is read optically and written by combining magnetic and optical methods.


Semiconductor memory uses semiconductor-based integrated circuits to store information. A semiconductor memory chip may contain millions of tiny transistors or capacitors.


Paper data storage is a form of data storage, consisting of strip of papers or paper cards in which holes are punched to store data.


Media life

Media should be refreshed on a regular cycle within the lifetime for archival storage identified by the manufacturer or independent sources. Sample generic figures for lifetimes are given below.

D3 Magnetic tape: 1 - 50 years
DLT magnetic tape cartridge: 1 - 75 years
CD/DVD: 2 - 75 years
CD-ROM: 3 months - 30 years
Punched paper media: Depends on quality of paper, but in general more than magnetic media.


The best of all media as far as concern media life and data preservation?

In my research about what type of data storage media should I use for my simple, failure immune 4-bit digital computer made out of common TTL chips, I thought of all the above considerations. If data capacity can be kept low, punched systems may be of great interest.

The greater disadvantage of punched cards and tapes, is the paper medium which can be easily damaged. This disadvantage does not refer to the punching technology used, but to the medium where the punches have been made onto. If we could punch holes on another medium other than paper, then we could ensure a much much greater media life and consequently data preservation.

Aluminium is the third most abundant element, and the most abundant metal, in the Earth's crust. It is soft, durable, lightweight, ductile, malleable and non-ferrous metal. It is theoretically 100% recyclable without any loss of its natural qualities. It is almost always alloyed, which markedly improves its mechanical properties. Most importantly, it is remarkable for its ability to resist corrosion and it can be easily found on metal shops in different shapes, including different diameter square and cylindrical bars.

My radio amateur experience has shown me that whatever is made out of metal, like those WW2 military radio equipment, lasts much longer. The archaeological findings also shows us that whatever is engraved on non-corrosive metals or other hard material, lasts millions of years. The idea for ultra long lasting media, is to drill holes onto an card made out of a square piece of aluminium metal.



All the above, may give you an idea of why metal punched cards could be far superior in extreme environment surviving in comparison to the fragile media we use today for data storage. Of course, I have completely ignored the data capacity issue on this article, which is indeed ultra low on punched cards. But if data capacity does not need to be high and media surviving is more important, one should consider this idea.

Back to main site