ddr@flux.isr.alaska.edu (Donald D Rice) (05/16/91)
In article <1991May15.154453.26014@mlb.semi.harris.com> dcb@dave.mis.semi.harris.com (Dave Brillhart) writes: >I'm looking at a TLZ04 drive. > >It says 60m in the tape. This brings up a question. I'm using Genuine Digital DATs, which are marked as being 60m, which I would interpret as 60 meters. In various supply catalogs, though, you can buy DATs marked as 60, 90, or 120. Are these numbers referring to lengths in meters or times in minutes? Since traditional audio cassettes come in 60, 90, and 120 minute sizes, the DAT markings are kind of ambiguous. If 60 is the "standard DAT," what would be the effect of using the longer tapes? More capacity? More fouled tapes? Is there a distinction between tapes for audio and tapes for data in the DAT world? I haven't seen much in the way of audio DAT equipment, so I don't know if there are a lot of different grades of DATs available as there are for audio and video cassettes. -- Don Rice Internet: ddr@flux.isr.alaska.edu Geophysical Institute E-mail: fnddr@alaska.bitnet University of Alaska Phone: (907) 474-7569 Fairbanks, AK 99775 Loran: 64.86N 212.16E
bruce@opus.objy.com (Bruce Reed) (05/17/91)
I've used both standard audio and data DATs, though never DEC's. The audio tapes are marked in minutes and come in 60, 90, and 120 minute varieties. I've only seen the data version sold in 60 meter lengths. A 120 minute audio DAT is equivalent to the 60 meter data DAT. I ran a few capacity tests to verify the above and found that I could not reliably read a 90 minute audio DAT written on an HP DDS drive. I would think the length would only affect the capacity, so perhaps I had a bad tape to begin with. I can't make any performance claims for data versus audio DATs. I have written my 120 minute audio DATs several times and have no problems recovering data. I'm sure the data DATs have higher quality tape and superior shells, but I think the data versus audio distinction is more of a marketing ploy which allows tape manufacturers to charge twice as much. Incidentally, 8mm tapes are packaged and marketed in a similar way. A 120 minute "video quality" 8mm tape is equivalent to a 112 meter data tape. This format is not particularly known for it's long life (write retries on the first pass!) and I've found that the data variety wears just as bad as the audio tapes. -- Bruce Reed Objectivity Inc. bruce@objy.com | Duck em' if they can't Menlo Park, CA sun!objy!bruce | take a joke!
benseb@grumpy.sdsc.edu (Booker Bense) (05/17/91)
In article <1991May17.061139.5673@objy.com> bruce@opus.objy.com (Bruce Reed) writes: >I've used both standard audio and data DATs, though never DEC's. The >audio tapes are marked in minutes and come in 60, 90, and 120 minute >varieties. I've only seen the data version sold in 60 meter lengths. >A 120 minute audio DAT is equivalent to the 60 meter data DAT. > [stuff deleted ] - Well, we have a Trimarchi(?) DAT drive and I am unable to get it to store more than about 375~ Megabytes using either DEC 60m or Maxell 60m DAT tapes and both the ultrix and gnu tar. If some kind soul could send me a note on how to check the capacity of the DAT drive I would appreciate it. - Booker C. Bense prefered: benseb@grumpy.sdsc.edu "I think it's GOOD that everyone NeXT Mail: benseb@next.sdsc.edu becomes food " - Hobbes
ddr@flux.isr.alaska.edu (Donald D Rice) (05/18/91)
In article <1991May17.061139.5673@objy.com> bruce@opus.objy.com (Bruce Reed) writes: >I've used both standard audio and data DATs, though never DEC's. The >audio tapes are marked in minutes and come in 60, 90, and 120 minute >varieties. I've only seen the data version sold in 60 meter lengths. >A 120 minute audio DAT is equivalent to the 60 meter data DAT. > That would make sense. I got to thinking about it and it takes us about 90 minutes to dump about 800 MB, so 1.2 GB would take about 120 minutes... therefore 60m = 120 min = 1.2 GB. >I ran a few capacity tests to verify the above and found that I could >not reliably read a 90 minute audio DAT written on an HP DDS drive. I >would think the length would only affect the capacity, so perhaps I >had a bad tape to begin with. > Not necessarily. One vendor told me that their DAT drives would not work reliably with 45m tapes...didn't say why, but recommended using only 60m tapes. That's why I've stuck with DEC's tapes, which are clearly marked as 60m. Besides, their price is competitive. >I can't make any performance claims for data versus audio DATs. I have >written my 120 minute audio DATs several times and have no problems >recovering data. I'm sure the data DATs have higher quality tape and >superior shells, but I think the data versus audio distinction is more >of a marketing ploy which allows tape manufacturers to charge twice as >much. > I want one of those dual-purpose drives that plays audio DATs as well as doing data DATs so we can get use out of the drive between backups. I wonder if any of the "jukebox" data DATs can play audio tapes? Maybe even include disk jockey software..."the latest in AC (Artificial Cool) technology brings the Top Ten to your DECstation." I hope DEC's engineers are hard at work on the concept. You can tell, it is Friday and I'm ready for the weekend. > >-- >Bruce Reed >Objectivity Inc. bruce@objy.com | Duck em' if they can't >Menlo Park, CA sun!objy!bruce | take a joke! -- Don Rice Internet: ddr@flux.isr.alaska.edu Geophysical Institute E-mail: fnddr@alaska.bitnet University of Alaska Phone: (907) 474-7569 Fairbanks, AK 99775 Loran: 64.86N 212.16E