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Date:      Mon, 9 Aug 1999 13:04:00 -0600 (MDT)
From:      "Kenneth D. Merry" <ken@kdm.org>
To:        mike@sentex.net (Mike Tancsa)
Cc:        scsi@freebsd.org, questions@freebsd.org
Subject:   Re: External RAID boxes (was Re: AHC errors. Bad disk or bad  firmware, or bug in driver ?)
Message-ID:  <199908091904.NAA29799@panzer.kdm.org>
In-Reply-To: <3.0.5.32.19990809141220.01086510@staff.sentex.ca> from Mike Tancsa at "Aug 9, 1999 02:12:20 pm"

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Mike Tancsa wrote...
> At 11:28 AM 8/9/99 -0600, Kenneth D. Merry wrote:
> >Yeah, I understand, it takes a while to upgrade.
> >
> >As far as RAID boxes, I'm not sure I would recommend anything, because I
> >don't have any direct experience with external RAID boxes.
> >
> >I will throw out a couple of things, though:
> >
> >- Charles Sprickman <spork@super-g.com> has had a fair bit of trouble with
> >  multiple channels on a single CMD array.  I'm not sure whether he is
> >  still having problems.
> >
> >- On the other hand, Karl Denninger <karl@Denninger.Net>, has had good
> >  success with CMD controllers.
> >
> >- ftp.cdrom.com uses a Mylex external RAID controller, and I think other
> >  folks have gotten good results with them as well.  For a small caveat
> >  (i.e. you shouldn't normally run into this problem, but you could) see
> >  my mail exchange with Joe Greco from early July.  Just search for
> >  "DAC960SX" and you should see it.  The bug in question was a FreeBSD bug,
> >  not really a bug with the controller.
> >
> >- I've seen various people mention other external RAID controllers on the
> >  lists, but I can't remember which.  I'd suggest looking through the
> >  freebsd-scsi archives.
> >
> >I've never heard of a Legacy RAID box.  Does the 5-6K include the drives or
> >not?  And 8 gig drives?  One thing you don't want to skimp on is drive
> >quality...most 8 gig SCSI drives I remember seeing are pretty low-end.  I
> >would recommend sticking with high-end Seagate or IBM disks.
> 
> The exact price was $4700 Canadian, and then they wanted to charge me about
> $900 CDN per Segate Medalist or $1000CDN for I think the IBM Deskstar. So I
> guess, ~6500 USD with 5 drives 

Hmm, it sounds like they're going with low-end drives.  I'd stay away from
the Seagate Medalists, we've got quirk entries in the CAM transport layer
to attest to the firmware "quality" on the Medalist Pro.

I'd go with the IBM Deskstar, although I can't guarantee they're good,
there's probably a better chance of their firmware being okay than the
Seagate Medalists.

Most likely they've qualified both types of drive with their hardware, and
therefore they're sure those drives will work.

> >You'll want something that does tagged queueing, and handles a reasonable
> >number of transactions.  And, most importantly, you'll want a controller
> >without nasty firmware bugs. :)  FreeBSD/CAM has a tendency to expose
> >problems that don't crop up as often in other OSes.
> 
> Before making any commitments, I do plan to dejanews through as many
> threads as possible.  The legacy  (www.legacy.ca) box looks nice in that
> the warrentee is decent (overnight replacement from down the road from us
> for 3yrs), and the price seems nice.  But stability is what I am looking
> for most of all. +-$1K at that range is not that critical.. stability is
> the key for me.  I am not sure what I would end up paying for in the equiv.
> Mylex device.

Yes, I think stability is very important.  I would be slightly concerned
with Legacy's choice of drives.  More important than that, though, is how
good/stable the firmware on their RAID controller is.  i.e. how they handle
under load.  If you want to go with that solution, you may want to try to
get an evaluation unit first, so you can subject it to a higher than normal
operating load and see what happens.

Other folks have had success with Mylex controllers, and it might be
worthwhile going with one of those, along with some nice high-end drives.

Like I said before, though, I haven't had any direct experience with
external RAID boxes, so all I can talk about is what other folks have
mentioned.

Ken
-- 
Kenneth Merry
ken@kdm.org


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