Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!brl-adm!seismo!rochester!ken From: ken@rochester.UUCP Newsgroups: comp.misc,comp.periphs Subject: Summary of tape survey responses Message-ID: <26466@rochester.ARPA> Date: Sat, 28-Mar-87 08:03:39 EST Article-I.D.: rocheste.26466 Posted: Sat Mar 28 08:03:39 1987 Date-Received: Sun, 29-Mar-87 09:04:44 EST References: <4288@videovax.Tek.COM> <26172@rochester.ARPA> Reply-To: ken@rochester.UUCP (Ken Yap) Distribution: world Organization: U of Rochester, CS Dept, Rochester, NY Lines: 206 Xref: utgpu comp.misc:411 comp.periphs:295 Ok, I got a couple more responses to my request for tape ratings. I've decided to post what I have. But I'm still taking mail. Thanks to all who responded. Ken From: cmcl2!phri!roy (Roy Smith) We use almost exclusively BASF Endura. I'm not much of a magtape guru; we use it because it's relatively inexpensive and that's what our major supplier stocks. We used to use unbranded tape, i.e. Pryor's own brand which I'm told (by the sales rep) was manufactured by Wabash, but we've sworn off that. For the past few years we've been doing 1600 on a DEC TU-80; about 9 months ago we got our Suns and now do both 1600 and 6250 on their drive (a Fuji something-or-other). The TU-80 still gets daily use for dumps on the VAX. We've used 600, 1200, and 2400 foot reels for the past several years. Recently they started making BASF Endura in 300 foot reels (same reel as a 600 foot tape, but half empty) and we bought a few boxes of that to see how it works out. How well you maintain your drive is probably a big factor. We're kind of lax on that, but I clean off the heads and rollers on both drives occasionally; maybe every other month or so. We should probably do it more often, but I figure every time I pull the cover off the heads to get at them with a swap, that's one more chance to scratch them or something. So far, no complaints. We had some bad experiences when our TU-80 was new (getting write errors a few hundred feet into the tape and/or running off the beginning or end of the reel, past the EOT marker) with the BASF Endura, but I'm almost certain the fault was not in the tape but in the drive (DEC changed a board and the problem went away). I've got one level-0 dump which I can't read (on Endura), but that was made years ago when the TU-80 was new; it may very well have been either due to the drive or even operator error (we were new to 4.2 and dump then). Actually, the most recent bad thing I had happen to a tape was when I dropped it on the floor and broke the plastic reel. Good thing it was a new tape and didn't have anything on it. I'm curious about mechanical shocks and magtapes, but not willing to experiment with *my* data! We've been using the same set of 10 2400 foot tapes for daily dumps on the TU-80 for must be 3 years now. Figure each tape gets used about once every other week, so we're talking 75 passes through the machine for each tape. Of course, most of the tape doesn't get used, but the beginning of it does every time, and we havn't seen any problems. We use the same stuff for archival level-0 dumps too. We randomly pick a virgin tape, or if I've got some tapes that I don't need anymore, I use those. Most of the archival dumps never get looked at, so I don't actually know if they are readable, but on the occasions when I've needed to go back to old dumps, I've never had any problems (except for the one mentioned above). The bottom line, in my opinion, is that as long as you buy a name brand tape, you don't have to go ape-shit to get the absolute best quality you can buy. But, like I said, I'm not a tape expert. The only rule I obey without fail is that I *never* use a tape until it's had a chance to come up to room temperature, no matter how desperate I am for that new shipment. In the winter, those tapes are pretty damn frigid when they come off the truck (but why am I telling somebody in Rochester about winter?) Roy Smith, {allegra,cmcl2,philabs}!phri!roy From: [someone who prefers to be unnamed - Ken] Manufacturer: Memorex Brand: MRX IV Density you use: 1600 60% 6250 40% Tape length: 2400, or is it 3200? Comments: Very good price wise, but it seems to have have problems after about 40 reads/writes then gets progressivly worse. 7/10 frequency: daily 10% weekly backups 60% file transfers 5% archivals 25% From: "Wombat" Manufacturer: Graham Brand: Epoch IV (or Verituf) Density you use: 6250 (a lot) / 1600 (sometimes) Tape length: 2400 Comments: 9 -- I'd give it a 10, but occasionally I have trouble getting these puppies to auto-load, 'cause the leader sticks to the rest of the reel or gets a little chewed up---this could be a function of our tapedrives, tho'. I've never lost a bit from these tapes, and I've been using about a dozen of them over over the last 6 years on an occasional basis. They've survived a number of moves, lots of different tapedrives, and other sorts of abuse. Yes, I would trust my dissertation to one of these tapes. Rich Kulawiec, rsk@j.cc.purdue.edu, j.cc.purdue.edu!rsk From: seismo!gorgo.att.com!bsteve (on Monster Island) CDC 1600 BPI 2400 FT - several cases, mean errors was 8 over 1 year. Scotch 700 1600 BPI 2400 FT - several cases, mean errors was 2 over 1 year Graham Magnetics 1600 BPI 2400 FT - several cases, mean errors was 3 over 1 yea r Graham Magnetics 1600 BPI 2400 FT - several cases, mean errors 15 over 3 years DEC 1600 BPI 2400 FT - over several cases, mean errors was 9 over 1 year DEC 1600 BPI 2400 FT - over several cases, mean errors was 23 over 3 years Errors represent both CRC and parity errors recorded per tape, but do not represent a complete write and read of the media. All of the data was taken from backup error logs over a 3 year period. I am reluctant to rate them on a 1 to 10 scale since the performance varies dramatically over several years. The Graham Magnetics tapes varied from dramatically from lot to lot, while the Digital tapes were consistantly mediocre. I should add that the Digital tapes had by far the largest number of unrecoverable errors resulting in the disposal of the tape. Steve Blasingame (Oklahoma City) From: harvard!eplunix!ijs (Ishmael J. Stefanov-Wagner) Manufacturer: CDC Brand: Alpha Phi Density you use: 800 1600 6250 Tape length: 600 1200 2400 Comments: 9 Our standard workhorse tape Manufacturer: 3M Brand: Scotch 700 Density you use: 1600 Tape length: 1200 2400 Comments: 5 Gunks up guides and vacuum columns Manufacturer: unknown Brand: INMAC Standard Density you use: 800 Tape length: 2400 Comments: 1 Useful solely for Write-Only/Read-Never files |\___/| Ishmael J. Stefanov-Wagner From: [another anonymous contributor - Ken] Subject: Re: 3M Blackwatch Magtapes Manufacturer: 3M Brand: Blackwatch Size: 2400' Density: 6250 Usage (daily backup, weekly, etc): daily,weekly,monthly Rating (out of 10): ? Comments: No problems so far. We have used them for almost a year. We have needed to read them several times and have had no problems reading recent tape. We have not had the need (and lets hope we never do) to read old tapes. From: [yet another anonymous contributor - Ken] Manufacturer: BASF Brand: Endura Size: 2400' 10.5" Density: 6250, 1600 Usage (daily backup, weekly, etc): backup, tar archives Rating (out of 10): 3 Comments: maybe 1 in 30 bad out of the box. Wear out quickly, to point where can't read 5 or 10 places on tape. Sometimes read after write is OK, but can't read for a restore a month later Manufacturer: 3M Brand: 777 Size: 2400 Density: 1600 Usage (daily backup, weekly, etc): backup, tar archives Rating (out of 10): 2 Comments: wear out and go bad Manufacturer: 3M Brand: Black Watch Size: 2400 Density: 1600 Usage (daily backup, weekly, etc): backup, tar archives Rating (out of 10): 5 Comments: Pretty good, but occasionaly (1 in 30) bad out of the box. Manufacturer: Graham Magnetics Brand: Summit Size: 2400 Density: 6250, 1600 Usage (daily backup, weekly, etc): tar archives Rating (out of 10): 8 Comments: never any problem. Always work unless the tape drive malfunctions. Manufacturer: Graham Magnetics Brand: Epoch 480 Size: 2400 Density: 6250, 1600 Usage (daily backup, weekly, etc): tar archives Rating (out of 10): 9 Comments: never any problem. Always work unless the tape drive malfunctions. Manufacturer: Graham Magnetics Brand: Ultimag Size: 2400 Density: 6250, 1600 Usage (daily backup, weekly, etc): tar archives Rating (out of 10): 10 Comments: never any problem. Always work unless the tape drive malfunctions. I am told it has an impressive warranty: if tape fails and you lose the data, will pay up to $5,000 data recovery costs (re-keying, etc.). If true, this is impressive.