Date: Tue, 13 May 1997 07:28:29 +0200 From: j@uriah.heep.sax.de (J Wunsch) To: hackers@FreeBSD.ORG Subject: Re: GNU is not tar Message-ID: <19970513072829.EP06728@uriah.heep.sax.de> In-Reply-To: <33780356.486F@fps.biblos.unal.edu.co>; from Pedro F. Giffuni on May 12, 1997 22:59:50 -0700 References: <Pine.NEB.3.94.970512202649.6144A-100000@misery.sdf.com> <33780356.486F@fps.biblos.unal.edu.co>
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As Pedro F. Giffuni wrote: > mt(2?) didn't fix the blocksize either, but I'm not sure of that format: It's mt(1), and no, most today's tapes are variable blocksize anyway, you can't use mt to enforce their blocksize. `variable' means they record a block in exactly the same size as you pass it down to the write(2) command (well, up to a maximum which is currently still 64 KB in FreeBSD, to cope with the limitations of some older SCSI controllers). That's why your application needs to know the blocksize, not the tape driver. Variable-length recorded tapes need to be written with at least a similarly (or longer) sized read(2) syscall, or an error will occur. (The st(4) driver will also syslog the size mismatch.) -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)
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