Date: Mon, 8 Sep 1997 14:57:59 +0100 (BST) From: Richard Tobin <richard@cogsci.ed.ac.uk> To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch), freebsd-scsi@FreeBSD.ORG Subject: Re: Is this (SCSI) tape drive compatible with FreeBSD? Message-ID: <199709081357.OAA21518@stevenson.cogsci.ed.ac.uk> In-Reply-To: J Wunsch's message of Sun, 7 Sep 1997 18:55:36 %2B0200
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> > What is the scoop on TR-4 drives such as the HP T4000 and Seagate
> > T8000?
Incidentally, these drives are a QIC standard, and have something like
65 linear tracks. Of course, they don't take traditional QIC tapes.
> I wouldn't trust them much. The SCSI errors i've seen from those
> Travan tapes were suggesting a very lousy SCSI implementation.
> They've even omitted SCSI commands that are clearly marked being
> mandatory by the standard, let alone the usual optional commands most
> drives do actually implement.
Well, The only SCSI command problems I encountered were
(1) doesn't implement "prevent media removal" which is optional
(2) doesn't accept PF=0 in mode select, which is the old SCSI-1
vendor-specific mode.
I have an HP T4000s and I can't unreservedly recommend it. Mine
stopped working (continual shoe-shining after restoring a few hundred
MB) and the HP technical support response was "we don't support it
under unix". When I explained that it was clearly a hardware problem,
they said it must be that my "unix files" were "corrupt". Eventually
I talked to a supervisor who agreed to accept the drive for testing,
and last week they phoned to say that yes it is faulty and they will
send me a replacement.
> > What is it about DAT or 8MM drives of similar capacity
> > and read/write speed (on the spec sheet at least) that makes them
> > cost about 50% more?
> Ask the question the other way round: why are thos Travan tapes that
> cheap if proven good mechanics still costs an arm and a leg?
You answered that question yourself, Joerg! The Travan drives are
much cheaper than helical scan drives because the mechanics are much
simpler. I would guess the hard part is making them reliably read and
write tracks less than 0.1 mm apart.
BTW, the T4000s seems to have a "training table" stored in the firmware.
Does anyone know exactly what this is?
-- Richard
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