There have been a number of comments lately about the permanence of recording media. I thought it might be useful to have some actual data. I should mention that I have over 40 years experience with backing up computer data, using mostly magnetic media until about 15 years ago, when I switched to CDs. There are several kinds of tapes available, and their failure modes are different. Basically, there are two kinds: 1) "Streaming" tapes, on which the data is recorded continuously, without any pauses until the copying is finished. 2) Block-data tapes, in which the information is organized into fixed- size blocks and each block is recorded independently. Note that this operation may APPEAR to be continuous, like the streaming tapes, due to the fact that the computer will usually start recording the next block before stopping after recording the previous one. 2A) A subset of the block tapes is the DECtape, a proprietary format of Digital Equipment Corporation. My experience suggests the following: 1) DON'T use "Streaming" tapes! They are fast and very convenient, although limited in the size of devices they can copy. However, a SINGLE point-failure can render the ENTIRE tape useless! 2) Ordinary "9-track" tape suffers mainly from "print-through", in which the data magnetically recorded on the tape in the tape wound OVER the tape section in question acts as a recording head and partially overwrites the data in question. You combat this by rewinding the tape frequently - at least once a year - which slightly shifts the position of neighboring data, so you don't always have the SAME data trying to overwrite. By being coreful this way, I have managed to keep data for as much as 20 years. I have not tried any longer period - it might work or it might not. 3) DECtape is superb - it doesn't seem possible to scramble it, probably due to extensive data-correction. I once managed to recover nearly all the data from a DECtape that had suffered physical damage - one quarter inch STRETCHED, due to a power failure while running at high speed. Unfortunately: a) DEC is extinct. You can't get the drives any more, and the ones that still exist don't use the standard busses. b) They don't hold much data. 4) The criticism of CDs is correct, if somewhat exaggerated. To test this, I dug out my oldest CDs - 3 of them, recorded on 14 Aug 1997 - and tried reading them. Results: Two of them read completely, without difficulty. One of them had a number of local problems i.e. single files that could not be read. My suggestion - if you wish to keep data on CDs for an extended length of time, make two or more copies. I should mention that I have always used the cheapest media I could find. Dan Killoran