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Re: What do you know about tapes...?

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On Friday, August 5, 1988 at 12:29:19 AM UTC-7, Carl S. Gutekunst wrote:
> In article <2...@execu.UUCP> de...@execu.UUCP (Dewey Henize) writes:
> >The question is, though, are we going to run into this same level of [tape]
> >incompatability with various *nix machines?
> Generally, one of the beauties of Unix tape handling is its incredible sim-
> plicity. And, the biggest headache is its incredible simplicity....
> A Unix raw tape device is very much a "you asked for it, you got it" device.
> You can write anything you want, byte-for-byte, in any size block, up to the
> limit of the buffers on the tape controller. Inter-record gaps get written
> after each write(2) call, and an EOF mark gets writen when the file is closed
> (if you had it open for write). You just can't get simpler than this. 
> The other edge of the sword is that if you want to do anything "standard,"
> like an ANSI format tape or plain ol' 80-block-40, you have to write an
> application to do it for you. The operating system won't help. The Unix dd(1)
> utility is supposed to assist in this sort of thing, although I've found that
> for any given new tape format, I have to write a C program to manipulate it.
> Someday someone write a really good tape handler for UNIX, and get rich....
> Differences are found in the controller's buffer size, which determines the
> maximum record size. You need at least 10K for the tar(1) utility to work, and
> the smallest I've seen on any Unix system is 20K. Pyramids allow up to 30K
> with the old IOC tape controller, and 64K with the TPE. Suns write up to 61K
> blocks on their Archive 1/4" tape; I dunno about their 1/2" 9-track interface.
> The other difference is how the physical end-of-tape is handled. Most UNIX
> systems botch this horribly, something like writing a record across the gap
> (good) but not allowing you to read it (bad). If this is important, ask your
> salescritter. (I am told Pyramid does this "right," meaning the same as most
> commercial DP machines, but I don't recall what "right" is. I do know that
> multi-volume cpio works flawlessly, which is not true on many other Unix boxes
> I have used.) 
> <csg>
Tape was a good back up medium. Now it's cloud. 

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Re: What do you know about tapes...? KP KP <jungletrain@outlook.com> - 2022-08-14 12:52 -0700

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