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Date:      Mon, 4 May 2020 00:03:36 +0200
From:      Arne Steinkamm <freebsd-questions@Steinkamm.COM>
To:        Christoph Kukulies <kuku@kukulies.org>
Cc:        freebsd-questions@freebsd.org, arne@steinkamm.com
Subject:   Re: dd: /dev/cd0: Invalid argument
Message-ID:  <20200503220336.GG82984@trajan.stk.cx>
In-Reply-To: <B0B4F1EA-8BAC-467F-A399-A0DC2720C149@kukulies.org>
References:  <B0B4F1EA-8BAC-467F-A399-A0DC2720C149@kukulies.org>

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Hi,

On Sun, May 03, 2020 at 09:56:16PM +0200, Christoph Kukulies wrote:
> I got a bit further with seeing my old SCSI-Periphals on the external SCSI bus connected to the sym0 (ASUS SC-200 Interface).
> 
> I can dd one of the disks connected there (/dev/da0) completely (2GB)
> 
> But I cannot dd if=/dev/cd0 of=cd_dump 
> 
> Doing this, I???m getting 
> 
> $ dd if=/dev/cd0 of=cd_dump
> dd: /dev/cd0: Invalid argument
> 0+0 records in
> 0+0 records out
> 0 bytes transferred in 0.000199 secs (0 bytes/sec)
> $ 
> 
> What???s wrong? /dev/da0 and /dev/cd0 are both character devices. I can well cat /dev/cd0 >dump .

The blocksize of CDs is 2k so use 2k or a multiplier of it.

  dd if=/dev/cd0 ibs=2k of=cd_dump

.//. Arne

-- 
Arne Steinkamm         | Home:     Mail: arne<at>steinkamm<dot>com



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