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Date:      Thu, 19 Mar 2009 10:55:27 -0700
From:      Chuck Swiger <>
To:        Jaime <>
Subject:   Re: Formatting a tape?
Message-ID:  <>
In-Reply-To: <>
References:  <>

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On Mar 19, 2009, at 9:15 AM, Jaime wrote:
> I have a DLT tape drive in a FreeBSD system.  With one of the tapes, I
> can get "tar -cvpf /dev/sa0 -C / ." to work.  With all the other
> tapes, I can't.
> Is there some kind of formatting process that I need to do?  I tried
> "mt fsf 1" from this page:

What's the SCSI controller that you're using, and which version of the  
OS are you running?
What's "mt status" say?  Can you try "mt blocksize 0", "mt rewind",  
"mt weof 2", "mt rewind" and then retry tar?

Try changing your blocksize via tar's -b flag to 32, 64, 126, or 128  
blocks.  FreeBSD doesn't expose enabling/disabling hardware  
compression or tuning compression levels via the device name used (ala  
Solaris' /dev/rmt/0ubn for example), so you'll need to look to "mt  
blocksize" and "mt comp" to adjust, otherwise you'll get whatever  
default behavior the device is set to.  In most cases, the device will  
want a fairly large blocksize in order to keep streaming the tape.

(I've used both Quantum DLT and sDLT drives with FreeBSD 5.x & 6.x on  
various Adaptec & LSI MegaRAID SCSI controllers-- mostly Dell, some HP  


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