tim@watson.bcm.tmc.edu (Timothy Owen Lesniak) (09/01/90)
I'm trying to determine the best type of media to use for backing up essential files for a disaster recovery plan. One of the factors I need to think about is the amount of data each of the availabe media can hold. Can anyone out there tell me how much the following will hold (in megabytes): TK70 TK50 1/2" (reel-to-reel on a TU81 at 6250 bpi) Also, can anyone tell me where I can find this information for future reference. Thanks, Tim tim@bcm.tmc.edu P.S. We currently use 8mm tape drive to do our regular backups, but we need to be able to have some data on one of the three previously mentioned\ media types since there aren't many 8mm drives on other systems that we could recover to.
mike@raven.uss.tek.com (Mike Ewan) (09/01/90)
In article <1806@gazette.bcm.tmc.edu> tim@watson.bcm.tmc.edu (Timothy Owen Lesniak) writes: > [...] >TK70 I believe this is 128Mb. >TK50 This is somewhere between 60 and 90Mb depending on how fast you stream the data to the device. The above are listed in the DEC Direct catalog. >1/2" (reel-to-reel on a TU81 at 6250 bpi) Tape_length_in_feet * 12 * density. A 2400 foot tape will be 180Mb. -- Michael Ewan (503)627-6468 Internet: mike@raven.USS.TEK.COM Unix Systems Support UUCP: ...!tektronix!puffin!raven!mike Tektronix, Inc. Compuserve: 73747,2304 "Fig Newton: The force required to accelerate a fig 39.37 inches/sec."--J. Hart
hbo@sbphy.ucsb.edu..ucsb.edu (Howard B Owen) (09/02/90)
In article <6491@tekgen.BV.TEK.COM> mike@raven.uss.tek.com (Mike Ewan) writes: >In article <1806@gazette.bcm.tmc.edu> tim@watson.bcm.tmc.edu (Timothy Owen Lesniak) writes: >> [...] > >>TK70 >I believe this is 128Mb. > The tape labels distributed by DEC say 298Mb. >>TK50 >This is somewhere between 60 and 90Mb depending on how fast you >stream the data to the device. > I vaguely recall someone claiming that TK50 cartridges could be used at TK70 densities if only a certain magic sequence were followed. Given the difference in cost between TK70 carts from DEC and TK50s from 3M, using the latter could result in substantial savings. Does anyone know if this is possible? If so, are there any problems related to media quality that might make the cartridge II tapes a good idea despite the extra cost? -- Howard Owen, Computer Systems Manager internet: hbo@sbphy.ucsb.edu Physics Computer Services BITNET: HBO@VOODOO.BITNET University of California, Santa Barbara HEPNET/SPAN: VOODOO::HBO "I am not a pay TV service!" 805-893-8366 (work) -- Howard Owen, Computer Systems Manager internet: hbo@sbphy.ucsb.edu Physics Computer Services BITNET: HBO@VOODOO.BITNET University of California, Santa Barbara HEPNET/SPAN: VOODOO::HBO "I am not a pay TV service!" 805-893-8366 (work)
alan@mq.UUCP (Alan H. Mintz) (09/03/90)
In article <1806@gazette.bcm.tmc.edu>, tim@watson.bcm.tmc.edu (Timothy Owen Lesniak) writes: > each of the availabe media can hold. Can anyone out there > tell me how much the following will hold (in megabytes): > > TK70 > TK50 > 1/2" (reel-to-reel on a TU81 at 6250 bpi) > From the DEC Systems/Options Catalog (March 1990): TK70 - 296 Mb (Formatted) TK50 - 95/96 Mb (Formatted) (I guess they can't decide which :-) TU81 - 145 Mb @ 2400' @ 6250bpi -- < Alan H. Mintz | Voice +1 714 980 1034 > < Micro-Quick Systems, Inc. | FAX +1 714 944 3995 > < 10384 Hillside Road | uucp: ...!uunet!mq!alan > < Alta Loma, CA 91701 USA | Internet: alan@MQ.COM >
alan@mq.UUCP (Alan H. Mintz) (09/03/90)
In article <6215@hub.ucsb.edu>, hbo@sbphy.ucsb.edu..ucsb.edu (Howard B Owen) writes: > I vaguely recall someone claiming that TK50 cartridges could be used > at TK70 densities... From what I've heard, this is the same think as using DD diskettes as HD diskettes. You can do it, but is the extra risk to your data (especially on BACKUP MEDIA) really worth the savings ? -- < Alan H. Mintz | Voice +1 714 980 1034 > < Micro-Quick Systems, Inc. | FAX +1 714 944 3995 > < 10384 Hillside Road | uucp: ...!uunet!mq!alan > < Alta Loma, CA 91701 USA | Internet: alan@MQ.COM >
bruce@ccavax.camb.com (09/05/90)
In article <6215@hub.ucsb.edu>, hbo@sbphy.ucsb.edu..ucsb.edu (Howard B Owen) writes: > I vaguely recall someone claiming that TK50 cartridges could be used > at TK70 densities if only a certain magic sequence were followed. Given > the difference in cost between TK70 carts from DEC and TK50s from 3M, > using the latter could result in substantial savings. Does anyone know The TK50 and TK70 tapes are similar, BUT to write one format on a tape already in the other format requires the tape being bulk erased first. Bulk erased or virgin tape can be used in either drive. The TK70 tolerances and tighter, and the tape it self may be different (not sure), but I think DEC is now only making the TK70 grade stuff. S/W distribution from DEC will always be in TK50 format, but may be on the better media. Just wait though! We are probably going to get yet another member to the family that will only be able to read the TK50 and TK70 tapes, but will be able to write its own type. I assume it will be even tighter tolerences, but maybe the coating formulation changes too.