On Sun, 4 Jun 2000, Johnny Billquist wrote:

> On 4 Jun 2000, Eric Smith wrote:
> 
> > > does it work if you remove the z option in tar. I have experience some
> > > problems with my dds2 and dds3 when trying to apply gnuzip to the tar
> > > archive. I have a ultrix with a tk50 i can do some research in this area
> > > later and tell how it reacts to the option z in tar.
> > 
> > I'm not disputing that there might be a problem, since I haven't tried
> > it myself, but the very concept that a TK50 might have problems with
> > the gnutar -z option amazes me.  How would the TK50 even "know"?
> 
> Let me put it this way: It's not about TK50 knowing about the -z option,
> it's about gzip not knowing about tapes...
> Unix by default act like an idiot when we talk tapes. tar *knows* about
> tapes, and can handle them much better. However, if you add the -z option,
> tar knows it's talking to a pipe instead, so you loose tar's tape
> handling. Instead you get the data to gzip, and gzip is a stupid program.
> 
> I would say that by using the -z option, you will actually get less data
> into the tape than if you run uncompressed data.
> This has to do with block size and inter-records gaps. If anyone want to,
> we can go deeper into this story, otherwise: just trust me. :-)
> 
> Simply put: don't use -z when writing to tapes.

	You may be able to play some games with piping the output through
	'|dd obs=126b > /dev/tapedevice'....


		David/absolute
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