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Date:      Thu, 29 Oct 1998 13:35:02 -0800 (PST)
From:      Tom <tom@uniserve.com>
To:        Rich Winkel <rich@chumbly.math.missouri.edu>
Cc:        stable@FreeBSD.ORG
Subject:   Re: RAID support in FBSD?
Message-ID:  <Pine.BSF.4.02A.9810291312000.5325-100000@shell.uniserve.ca>
In-Reply-To: <199810292052.OAA16290@chumbly.math.missouri.edu>

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On Thu, 29 Oct 1998, Rich Winkel wrote:

> I'm new to this raid stuff.  I understand you can get a raid which
> hooks to the scsi bus and looks to the computer like an ordinary
> (albeit fast) disk.  Theoretically this would work without any specific
> OS support, right?

  More than theory.  They work.

  Disadvantages:  limited by speed of the RAID box host bus.  More
overhead before data hits the disk.

  Advantages:  you can configure the unit from an LCD panel, or VT100
terminal.  No need to run special software on your server.

> The alternative would be a raid card on the PCI bus, which can move
> data faster, but would require OS driver support.
> 
> Of course there's a lot to be said for OS-independent hardware, but
> aside from the faster speed, are there worthwhile advantages (i.e.
> access to special features) to be gained by going with a PCI raid
> card?  I understand fbsd supports DPT pci controllers.  How do
> they compare with the competition?

  DPT has a whole line of host based RAID controllers.  They are probably
the best you can get.  Very wide operating system support, so they are
hardly OS depedent.

  Disadvantages:  FreeBSD can't run the dptmgr software, so online
re-config and monitoring is not possible.  If, you have a smart drive
enclosure, this shouldn't be a big problem.

  Advantages:  a DPT PM334 is probably cheaper than a SCSI-SCSI raid unit.
It also doesn't need any precious hard bays to be mounted in either.  You
also get up to 3 UW SCSI channels per PCI slot.

> The machine would be a 400mhz xeon, a departmental server, with
> an adaptec 2940 ultra wide/fast controller.
> 
> Sorry for the open-ended questions, any faq pointers would be
> much appreciated.
> 
> Thanks for any help!!!
> 
> Rich
> 

Tom


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