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copy tape to tape

Hi all,
I need to copy 1 tape (/dev/st0) to another tape (/dev/st1).
I tried to do it using the command
dd if=/dev/st0 of=dev/st1
but it doesn't work
The tapes I have to copy are writte with 128 blocking and I use the
line
tar -b 128 -xvf /dev/st0
to extract them.
Could you help me please?
How can I copy this tape???
Thank you very much
Riccardo

0
6/5/2007 1:34:16 PM
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On Tue, 05 Jun 2007 06:34:16 -0700, riccardo wrote:

> Hi all,
> I need to copy 1 tape (/dev/st0) to another tape (/dev/st1).
> I tried to do it using the command
> dd if=/dev/st0 of=dev/st1
> but it doesn't work
> The tapes I have to copy are writte with 128 blocking and I use the
> line
> tar -b 128 -xvf /dev/st0
> to extract them.
> Could you help me please?
> How can I copy this tape???
> Thank you very much
> Riccardo
>
Caveat: I have never used tape drives with GNU/Linux.

The block size may be required as an input to dd. man dd. It appears
to me, that your first attempt with dd would probably work if the
correct block size were specified.

Also, if introducing tar (for whatever reason) verify you are
specifying the block size correctly. man tar. The -b switch specifies a
block size as N*512 (default N=20). That could be a source of the
failure if incompatible block sizes were used. For example, are you sure
that 'tar -b 256' would not be appropriate? As I said, I don't know
anything about tape, though.

I found this FAQ with general info for restoring tapes:
http://www.faqs.org/faqs/aix-faq/part2/section-1.html

-- 
Douglas Mayne



0
doug8182 (286)
6/5/2007 2:24:50 PM
Douglas Mayne staggered into the Black Sun and said:
> On Tue, 05 Jun 2007 06:34:16 -0700, riccardo wrote:
>> dd if=/dev/st0 of=dev/st1
>> doesn't work
>> The tapes I have to copy are writte with 128 blocking and I use
>> "tar -b 128 -xvf /dev/st0" to extract them.
> The block size may be required as an input to dd. man dd. It appears
> to me, that your first attempt with dd would probably work if the
> correct block size were specified.

Yes.  When I tried to retrieve data from a tape that had been written
in some sort of weird proprietary format, I had to do "dd if=/dev/st0
bs=64k ..." to get anything rational out.  If you don't specify the bs,
dd assumes 512 bytes.

> verify you are specifying the block size correctly. man tar. The -b
> switch specifies a block size as N*512 (default N=20). That could be a
> source of the failure if incompatible block sizes were used.

So you'd use bs=64k here.  I think.  While I've used dd to read from
tapes, I've never used dd to try to write a tape.  You *may* need to do
"mt setblk" on the new tape.  See what "mt status" reports for a
blocksize on the old tape.

> http://www.faqs.org/faqs/aix-faq/part2/section-1.html

AIX?  Holy crap.  The stuff that isn't AIX-specific (SMIT commands,
tctl, etcetera) looks reasonably useful, though.

-- 
   I think I'll go hold my head under a bucket of vodka until I feel
   better.
   --localroger on kuro5hin.org, 06/26/2003
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
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6/5/2007 2:41:53 PM
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