Newsgroups: comp.unix.admin Path: utzoo!utgpu!watserv1!watmath!mwtilden From: mwtilden@watmath.waterloo.edu (Mark W. Tilden) Subject: Re: Reliability Exabyte tapes Message-ID: <1991Mar4.031555.22529@watmath.waterloo.edu> Organization: University of Waterloo References: <3235@canisius.UUCP> <7HKYJ54@dri.com> <1991Feb27.191216.5859@sobeco.com> Date: Mon, 4 Mar 1991 03:15:55 GMT Lines: 47 In article braun@dri.com (Kral) writes: >In article <1991Feb27.191216.5859@sobeco.com> sdesmara@sobeco.com (s.desmarais) writes: >>Speaking of reliability, I'd like to know what is the reliability and the >>durability of the exabyte media. What will happen in 15 years when I want >>to restore files from exabytes? (Recently, we restored a 14 years old file >>from a 9-track tape.) > >My advice: you should always "check" any wound, streaming magnetic media at >least every 24 months. By this I mean at least rewinding the tape, but >possibly rewriting it as well. Otherwise, you stand the chance of the data >bleeding onto the next layer of tape and causing parity problems. > Basing the lifetime of Exabyte media against it's immediate video counterpart means that you can expect a lifetime of at least 25 years or 600 play/rewinds before the tape looses the 7dB signal loss which will result in fatal restore errors. This does not take into account scratches or tape folds that can be introduced to the tape by faulty or wearing tape mechanisms (a real problem as current Exabyte units only last approx 1000 running hours before they become tape 'hostile'). Modern 8mm tape, especially the high-metal variety used in Exabytes, actually has very low magnetic bleedthrough in comparison to other video formats like beta and especially VHS, because of the extreme density and uniformity of the metal crystals, and superior seperation between tape layers by a tape backing as thick as the magnetic media itself. Exabyte tapes are so reliable in fact that you could hold them to your filing cabinet with a (appropriately sized) fridge magnet and still be fairly sure of getting your data back (No warrenties expressed or implied). The biggest danger is mechanical wear or damage. The less you play a tape, the better off it'll be, at least until Exabyte starts using improved Hi8 video mechanisms in their product. So the answer is you're in pretty good shape if you back up every two years or leave your tape on a shelf for twenty. The biggest danger will be if there'll be anything to read your quaint 'tape' come the year 2010. It should be safe enough until r/w diskmans come onto the scene. Is all. -- Mark Tilden: _-_-_-__--__--_ /(glitch!) M.F.C.F Hardware Design Lab. -_-___ | \ /\/ U of Waterloo. Ont. Can, N2L-3G1 |__-_-_-| \/ (519) - 885 - 1211 ext.2454, "MY OPINIONS, YOU HEAR!? MINE! MINE! MINE! MINE! MINE! AH HAHAHAHAHAHAHAHAHA!!"