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Date:      Tue, 17 May 2005 15:14:11 -0700
From:      Kris Kennaway <kris@obsecurity.org>
To:        Jerry McAllister <jerrymc@clunix.cl.msu.edu>
Cc:        Kris Kennaway <kris@obsecurity.org>
Subject:   Re: Transferring dump file to tape?
Message-ID:  <20050517221411.GA1499@xor.obsecurity.org>
In-Reply-To: <200505171259.j4HCxavZ029551@clunix.cl.msu.edu>
References:  <1220.66.25.129.27.1116333880.squirrel@mail.cm.utexas.edu> <200505171259.j4HCxavZ029551@clunix.cl.msu.edu>

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On Tue, May 17, 2005 at 08:59:36AM -0400, Jerry McAllister wrote:

> > Thanks for your input. As per Kris' suggestion adding the
> > blocksize worked for me. 'mt' reports my tapedrive having
> > a blocksize of 1024 bytes (1k), so my command was
> >=20
> >   dd if=3Dvar-200501516 of=3D/dev/nsa0 bs=3D1k
> >=20
> > I transfered the dump file to tape and then was able to
> > restore directly from tape. My test dump file was small
> > (140K) but today I plan to test with a full-size
> > multi-gigabyte dump file. I haven't played long with dd to
> > judge its reliability. While I was looking around, I also
> > came across sdd (/usr/ports/sysutils/sdd), which claims to
> > be a better dd replacement.
>=20
> Adjusting the blocksize was my suggestion.

Also mine :0

> But, even doing that doesn't fix the problem we often see with
> writes to tape failing in that manner.=20
>=20
> dd itself is reliable.   It is tried and true.   I think our
> failures come from something in the sa driver because a drive
> that fails usually fails for everything except maybe tar and dump.

Are you absolutely certain that the tape device is not in use at the
time that the application receives the error?

Kris

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