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Date:      Fri, 7 May 1999 13:39:00 -0500
From:      Karl Denninger <karl@Denninger.Net>
To:        mjacob@feral.com
Cc:        Darryl Okahata <darrylo@sr.hp.com>, freebsd-scsi@FreeBSD.ORG
Subject:   Re: Question - Onstream SCSI Streamer
Message-ID:  <19990507133900.A317@Denninger.Net>
In-Reply-To: <Pine.LNX.4.04.9905071131460.1661-100000@feral.com>; from Matthew Jacob on Fri, May 07, 1999 at 11:32:15AM -0700
References:  <19990507133118.B266@Denninger.Net> <Pine.LNX.4.04.9905071131460.1661-100000@feral.com>

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On Fri, May 07, 1999 at 11:32:15AM -0700, Matthew Jacob wrote:
> 
> > > > "low-cost drive with a proprietary interface".  Even though it has a
> > > > SCSI connector, it's not a tape drive in the traditional (SCSI) sense.
> > > > It'll take special drivers to talk to this puppy.
> > > > 
> > > >      If you're feeling brave and lucky, OnStream is selling "new"
> > > > internal Quantum DLT-2000XT's for $649 (15GB capacity, uncompressed	).
> > > > Note that these are "brand new" obsolete drives.  You'd better read the
> > > > fine print (especially on warranty, shipping, and "defective products"),
> > > > but check out:
> > > 
> > > I would not recommend the XT given the media incompatibilities they've
> > > been known to have.
> > 
> > The XTs are fine - but they cannot read or write tapes written on a 
> > DLT 4000 or 7000.
> > 
> > They can read and write 10GB (2000) and 15GB (DLTIII-XT) media, along with
> > older DLT formats.
> > 
> > The big problem with the 2000XTs is the cost and availability of the tapes.
> > To get full capacity you need the XT length tapes (15GB) which are NOT 
> > second-sourced.  As such you're going to get positively raped on the 
> > media cost since there is no competition (no Fuji tapes, for example).
> > 
> > I had two of these at MCS - they were rock-solid and reliable.  However,
> > unless you can reliably source media they're going to be trouble down the
> > road.
> 
> I had several at Legato. By mistake an XT tape placed into a 2000
> destroyed it.

Well, yes.  The XT tapes are both thinner and longer than the regular 
2000-series DLT tapes, and the 2000-series drives CANNOT handle the 
thinner and longer media.

DLT in general is *forward* compatible, but not *backward* compatible.

This is also true of most other "similar" media types (ie: put a 120mm
DDS-II tape in an older DDS drive and it will get "eaten" as well, 
as the proper running tension is MUCH lower on the 120mm media)

I have NOT tried putting a 2000-XT tape in a DLT-4000 unit, and have
absolutely no idea if that is safe or not.  If its not then the drive
is a dead end, which could be bad.

One of the items that makes these new "Onstream" drives so attractive is
the price.  $500 for the drive is damn good, and with media about $1/Gb
its quite competitive.  The 50G version of the same drive, due out sometime
this second quarter can handle an "extra length" cartridge - but is also
backward compatible for both read an write.

The Onstreams are also about as fast as a DLT 4000 (but not as fast as the
DLT 7000) in terms of raw I/O bitrate, and their media is less expensive.

I wouldn't be surprised if they end up being a dominant device in the
low and midrange server marketplace.  On a cost/performance basis nothing
else on the market comes close.

--
-- 
Karl Denninger (karl@denninger.net)  Web: fathers.denninger.net
I ain't even *authorized* to speak for anyone other than myself, so give
up now on trying to associate my words with any particular organization.


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