Path: utzoo!mnetor!uunet!husc6!bbn!rochester!udel!princeton!phoenix!paul From: paul@phoenix.Princeton.EDU (Paul Lansky) Newsgroups: comp.periphs Subject: Re: How reliable is video tape and DAT tape (for data storage) Message-ID: <2046@phoenix.Princeton.EDU> Date: 12 Mar 88 02:03:12 GMT References: Organization: Princeton University, NJ Lines: 42 Summary: experiences with tapes In article , jw@sics.se (Johan Widen) writes: > [ This article was posted 21 Feb 88 06:53:16 GMT but was stopped on a machine ] > > I was recently told that the rotating read/record heads in video tape players > are quite abrasive and that they tend to destroy the video tape in as little > as 10 passes. I was also told that the situation is even worse with DAT > (Digital Audio Tape). I've worked with lots of different kinds of tapes over the years (I'm in computer music), lots of 1600BPI, 6250s, audio tapes, VHS and BETA formats for video and PCM, TK50s etc. The tapes I have had the most difficulty with have been BETA/PCM, using exactly the head technology that is used in DAT and the new 8MM VHS/2.3GIG storage systems. The PCM formats have massive error correction built in, but I have found that about 70% of the time if a tape is played more than 10 times or so, bad spots will start to develop because of the abrasiveness of the rotating heads. I don't know what kind of error correction the new backup systems use but given the density at which data is stored I think one bad spot will lose a LOT of information. But, once you realize that data is probably more fragile on these tapes the following precautions will probably make them as robust as other tape storage media. 1) Buy only the highest quality tape. For our PCM systems I use tape no longer than L500 in Beta. The longer tapes are thinner. I also recommend only using the highest quality. Sony-PRO tape is best. Given the cost of storage per Mbyte, even the MOST expensive tapes are a bargain. 2) If you have data that has to be archived and retrieved frequently from a given tape it is best to keep a master and work with copies of that master. We do this with PCM formats and it works quite well. I've stored many many gigabytes of signal files on 9-track tape over the past 15 years and only lost data once or twice, with careful use. I don't see how the new media can approach this level of reliability, particularly given the violent start/stop motion it is likely to undergo in various situations, but it is certainly worth a try. Paul Lansky Music Department Princeton University