Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site denelcor.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!houxm!houxz!vax135!cornell!uw-beaver!tektronix!hplabs!hao!denelcor!lmc From: lmc@denelcor.UUCP (Lyle McElhaney) Newsgroups: net.unix-wizards Subject: Re: 4.2 dist tape Message-ID: <535@denelcor.UUCP> Date: Sun, 19-Aug-84 23:15:05 EDT Article-I.D.: denelcor.535 Posted: Sun Aug 19 23:15:05 1984 Date-Received: Wed, 22-Aug-84 01:07:56 EDT References: <445@ittral.UUCP> Organization: Denelcor, Aurora, CO Lines: 31 Ah, yes, making an exact copy of a tape with Unix. Its easy enough if its a tar or cpio tape (provided you know that ahead of time), but what about the Univac tape you just received with one label on it, giving the returnee's address? The easiest thing to do is to use dd, as the referenced article stated, from one tape drive to another (with due regard to tape densities). If you set the buffer size higher than any physical record size on the tape, dd will make an exact copy of the tape file. We regularly copy tapes with the command: dd if=/dev/nrmt0 of=/dev/nrmt1 bs=21000 Yup, it wastes space on a non-virtual machine, but almost any machine that runs multitasking Unix (and has two tape drives) won't notice the difference. Now, the gentleman did have a valid gripe: why does the Berkeley setup manual (and others, probably) wisely say "make copies of the tapes" and then don't say how? We certainly aren't all guri when we start, as many of us have, becoming system admin's from a cold start. I have a tape utility called ts that describes the file/record layout of an arbitrary tape - so as I write a manual page I'll submit it to net.sources. In addition, I also wrote a utility for making a tape copy on a system with only one tape drive, as long as you have sufficient disk. Will post it too. PS: Michael P., where are you? -- Lyle McElhaney (hao,brl-bmd,nbires,csu-cs,scgvaxd)!denelcor!lmc