How long will tape, disk, CD data last?
This subject comes up every time some CP/M archive on the Web vanishes, or there is some discussion of data media. Of course some CP/M original media is 20 years or more old, so it is relevant. The issue in many cases is not the degration of the media, but loss of old technology and software to READ the media. A reasonable strategy is to copy data to “current” media every few years to avoid both media damage and obsolscence. A Web search on particular media and studies of reliability will find references to failure modes; I won’t list them here but I’ll review the issues briefly by media. Various studies of magnetic tapes suggest that tapes lose data in many ways over the course of years, particularly if the tapes are idle and stored in environments with varying temperatures. This is less true for diskettes, but data can still be lost over periods of years and decades. All magnetic media are damaged by magnetic fields of course. CD’s are either user-recorder (CD-R, CD-RW, etc.) or are
