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From: OBERMAN@LLL-ICDC.ARPA ("Kevin Oberman, LLNL,  422-6955, L-156", 415)
Newsgroups: comp.os.vms
Subject: RE: vhs backups
Message-ID: <8709230938.AA26553@ucbvax.Berkeley.EDU>
Date: Tue, 22-Sep-87 11:28:00 EDT
Article-I.D.: ucbvax.8709230938.AA26553
Posted: Tue Sep 22 11:28:00 1987
Date-Received: Sat, 26-Sep-87 00:45:21 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
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>     We are looking at several vendors who appear to have
>   a VHS backup capability (backup VAX/VMS data onto a standard
>   VHS tapes as opposed to reel mag tape)?  Anybody have any
>   experience/suggestions with this approach

One of the systems here is running the DIGI-DATA system. It costs about
$7K with UNIBUS controller and software. Less if you have a Pertec formatter
available.

So far, so good. It does the BACKUP of a 456 MB disk in about an hour and
15 minutes. A single tape hold about 1.2 GB. This is because we are driving
it with a 750. With a faster processor we might reach the specified 2.2 GB.
Since it has only been running for a month, I don't know about the shelf
life of the tapes, but I wouldn't try it as an archive system. Just paranoid,
I guess.

Because it does not stop-start well, it writes `white space' if the processor
can't keep the buffer loaded. This means that a fast CPU is needed to keep
the drive from wasting tape. And CRC on most systems would be a disaster.
Esp. on a uVAX. I suspect that a uVAX BACKUP with CRC would result in about
100 MB per tape. The unit does have hardware CRC.

I'm very interested in hearing about other's experiences as I want to get
more systems in the near future.

I've heard that systems based on the DAT tape format will be forthcoming
within a year. And these are supposed to be 5.25 form factor. They should
be able to fit in the space for a TK50/70. Doesn't a 2 GB tape on your uVAX
sound nice?

					R. Kevin Oberman
					Lawrence Livermore National Laboratory
					arpa: oberman@lll-icdc.arpa
   					(415) 422-6955

Disclaimer: I am not endorsing any product. I work for Uncle Sam and to do so
would make him upset. Neither my employer nor myself can take resposibility for
the accuracy of this information. I believe it is correct, but if it's not I
can only say "Sorry". I'm a rotten typist and a worse speller, so forgive
any silly errors.