rlm@ceres.physics.uiowa.edu (09/30/89)
I posted an inquiry a few weeks ago about 4mm DAT tape subsystems, but no one
seemed to have any experience. We have a VAX-3200 (Q-bus)+2x3100 (VMS) cluster
with some 1.5 GB of disk which we need to backup with minimal operator
intervention. The choices seem to be:
o Buy an 8mm Exabyte system. These are available in several packages
and are in wide use. I have been told that they are `fairly' reliable
but are extremely slow if one wants to recover selected file(s)
located in the middle of the tape. Also, the reliability is apparently
not terrific- I was told that it was comparable to a TK-50 (ouch!!).
o Buy a 4mm DAT system. These are apparently just becoming available for
VAX/VMS systems (although I haven't been able to contact anyone who has
used one yet). They have only 60% capacity per tape compared with 8mm
but are claimed to be more reliable (because of the digital recording
technique) and have much faster selective file recovery (20sec maximum).
We need to purchase something right away because at the moment we have NO
backup device. Can anyone offer useful suggestions on this subject? I
would be particularly interested in (a) First hand experience with a DAT
subsystem in a DEC environment (VMS) and/or (b) A consumer guide to the 8mm
systems- which is considered the most reliable, or the best buy?
Thanks in advance
Robert Mutel
Department of Physics and Astronomy
University of Iowa
Iowa City, IA 52242
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grr@cbmvax.UUCP (George Robbins) (10/05/89)
In article <21496.2524aa95@ceres.physics.uiowa.edu> rlm@ceres.physics.uiowa.edu writes: > I posted an inquiry a few weeks ago about 4mm DAT tape subsystems, but no one > seemed to have any experience. We have a VAX-3200 (Q-bus)+2x3100 (VMS) cluster > with some 1.5 GB of disk which we need to backup with minimal operator > intervention. The choices seem to be: > > We need to purchase something right away because at the moment we have NO > backup device... 8mm is a hell of a lot better than no backups. I don't know that the whole story is in, but many people are using them and even if something else turns out much better, I would expect the 8mm drives and technology to have at least a 3 year useful life. It's just too soon to tell about the DAT stuff - if you are brave, get one on a test basis, but the chances are much greater that the drive/company/format will be orphaned within a year... -- George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@uunet.uu.net Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)
hurf@batcomputer.tn.cornell.edu (Hurf Sheldon) (10/10/89)
In article <8101@cbmvax.UUCP> grr@cbmvax.UUCP (George Robbins) writes: >In article <21496.2524aa95@ceres.physics.uiowa.edu> rlm@ceres.physics.uiowa.edu writes: >> I posted an inquiry a few weeks ago about 4mm DAT tape subsystems, but no one >> seemed to have any experience. We have a VAX-3200 (Q-bus)+2x3100 (VMS) cluster >> with some 1.5 GB of disk which we need to backup with minimal operator >> intervention. The choices seem to be: >> >> We need to purchase something right away because at the moment we have NO >> backup device... > >8mm is a hell of a lot better than no backups. George, My biased opinion: 8mm is a hell of a lot better than ANY backups. I have used a Viking controller with Exabyte 8mm drive for 16 mos now, we do incrementals daily and level 0 biweekly on 7 systems contituting a total of 2gig of disk. We also have another system with 1gig and a Viking/Exabyte drive that has been in operation for 6 mos. Neither drive has ever burped. The dump tapes cost $8.99 for 2 gig vs over $500.00 for the same capacity in a tk50 plus it is a start and go process - put the tape in and go home. No poor animal has to wait around endless hours to change endless tapes. Restores of individual files ove 800meg into a tape has taken 15 mins at the outside. The savings in tape, labor and anxiety has paid for the drive & controller (About $4k a year ago) many times over. >least a 3 year useful life. It's just too soon to tell about the DAT stuff - >if you are brave, get one on a test basis, but the chances are much greater >that the drive/company/format will be orphaned within a year... > DAT's as far as I know won't hold the amount of data that the 8mm will so I don't see the 8mm being obsolete anytime soon. The low cost of operation probably won't be matched by DAT as the tapes will cost more and the drive may as well - it certianly will [cost more] in the beginning. Besides, I would still like to have a slick vacuum load 6250 reel tape at certian times and this is 1989... Because DAT is digital format, they no doubt will do 'tar -r' - which the analog format Exabytes won't do (which is why they are being mainly marketed as 'backup' devices) -they should be around to stay. The DAT will probably be a popular OEM item as it will replace completely any other drive currently being shipped. Hurf -- Hurf Sheldon Network: hurf@ionvax.tn.cornell.edu Lab of Plasma Studies Bitnet: hurf@CRNLION 369 Upson Hall, Cornell University, Ithaca, N.Y. 14853 ph:607 255 7267 I got a job in science; I bought a Porsche; Now, everyone takes me seriously.