Date: Sun, 25 Aug 1996 18:26:07 -0700 (PDT) From: Greg Lehey <grog> To: hoek@freenet.hamilton.on.ca Cc: freebsd-current@FreeBSD.org (FreeBSD-current users) Subject: Re: Help on block size in tar Message-ID: <199608260126.SAA05174@freefall.freebsd.org> In-Reply-To: <199608241406.KAA03455@james.freenet.hamilton.on.ca> from "hoek@freenet.hamilton.on.ca" at Aug 24, 96 10:06:40 am
next in thread | previous in thread | raw e-mail | index | archive | help
> > In Email, J Wunsch <j@uriah.heep.sax.de> wrote: > > > > What is the default blocksize of tar on FreeBSD, I have made a tape > > > > on a freebsd system and now cannot read it on a linux system. > > > > > it may be more complicated... > > > it might be teh TAPE DRIVE complaining... > > > > Anyway, i think the default blocksize is only 512 bytes. This should > > also pass any variable-length driver. > > Are you sure? I quote the tar manpage (which, being GNU tar isn't the > official source of information regarding tar, I suppose). > > "and 20 is the default block size" > > And each of these blocks are then 512 bytes, I believe. This is the traditonal tar format, at least as far back as the Sixth Edition. It's certainly true for the version of GNU tar I'm using, but that isn't the released version. I'd expect it to be true both for the -release version of tar, and also for Linux tar. > Or the manpage is just confusing the heck out of me. About the only thing it could be doing is lying. But I don't believe that. To the original poster: I think you're probably looking in the wrong place. Since Linux also uses GNU tar, you could try $ tar tvb 1 or $ tar tvb 20 and see if that helps. BTW: for helical scan tapes, you should use large block sizes, typically 64 or 128 blocks (use the b option for this, as well). Be warned, however, that some brain-dead System V tars can't read more than 62 (yup, 62) blocks. If you find you need to read big blocks on these bmachnes, dd might help you.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199608260126.SAA05174>