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From: Greg Lehey <grog@lemis.com>
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Subject: Re: Reading an Archive that was created on DEC.
In-Reply-To: <199708152006.QAA20404@arthur.ct-yardley.com> from rajesha at "Aug 15, 97 04:07:01 pm"
To: rajesha@ct-yardley.com (rajesha)
Date: Sat, 16 Aug 1997 16:32:13 +0930 (CST)
Cc: questions@FreeBSD.ORG
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rajesha writes:
> I am trouble reading the archive that was made on the DEC AlphaServer 1000
> which had a DEC proprietary tape drive.  The tape is a 4mm DAT and I am
> trying to read from a Sony 5000 Tape drive.

In all probability, the drive will not be particularly proprietary.

> When I made backup, I used 'tar -cv /*'.  I tried to list the archive using
> 'tar -t' and I get a block size error.

Interesting.  I wonder what they're doing.

> How does block size effect between different drives.

This isn't really a drive issue.  It's a tar issue.  Normal tars
expect a block size of 10240 K (20 "blocks" of 512 bytes).  Your DEC
machine obviously has a different default.

> I do not remember the block size when I created an archive.

If you just said 'tar -cf', you didn't specify a block size, and you
got the default.

Look on the console or in /var/log/messages.  Along with the message
on the terminal:

  tar: read error on /dev/nrst0 : Input/output error

you should get a message:

  Aug 16 16:30:53 freebie /kernel: st0: 65536-byte record too big

That's the blcok size.  This particular tape can be read with:

  tar tvb 128

The -b option specifies block sizes in "blocks" of 512 bytes.

Greg