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Date: Thu, 26 Dec 1996 11:14:53 -0800
From: Julian Elischer <julian@whistle.com>
Organization: Whistle Communications
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To: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de>
CC: FreeBSD-current users <freebsd-current@FreeBSD.ORG>
Subject: Re: DAT: reading with blocksize=256K
References: <199612261827.TAA03226@uriah.heep.sax.de>
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J Wunsch wrote:
> 
> As Heikki Suonsivu wrote:
> 
> > I have been able to read my old backups written with 1024k blocksize.  They
> > secret was to use ddd instead of dd.
> 
> This must be unrelated to the other problem.  If they were written
> with 1024 K blocksize on a FreeBSD machine, they were actually written
> with 64 KB instead.  The limit is in physio(9) (UTSL), and could not
> be changed by whatever trickery from a userland program.
> 
OR
the drive is in fixed block mode.
in FIXED block mode what is actually written to tape is fixed blocks
and many are written at a time for a large read/write

thus you can read and write differnt blocksizes because it always
ends up a multiple of hte smaller blocksize anyway..


julian