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Date:      Tue, 3 Feb 1998 08:42:45 +0100
From:      "Alex Chircop" <>
To:        "Tom" <>
Cc:        <current@FreeBSD.ORG>
Subject:   Re: RAID controllers - folks, check this thing out
Message-ID:  <000001bd3081$a38a34a0$>

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What drivers are you using for the DPT controllers ?


-----Original Message-----
From: Tom <>
To: Karl Denninger <>
Cc: current@FreeBSD.ORG <current@FreeBSD.ORG>
Date: Tuesday, February 03, 1998 2:10
Subject: Re: RAID controllers - folks, check this thing out

>On Fri, 30 Jan 1998, Karl Denninger wrote:
>> Remember a bit ago I was asking about RAID controllers?
>> Well, I found one.
>> Talk to Pacific Computer Expansions, a gentleman by the name of Warren at
>> 800-458-5058.
>> You want the CRD-5440.
>> This is a RAID 0, 0+1, 4 or 5 free-standing SCSI device.  It accepts
>> memory, and also has battery backup capabilities (attach a 6V Gelcel to
>  Just a standard SCSI-to-SCSI RAID device.  These have been around for
>years.  DEC, Mylex, and others have been making them for some
>> I have MEASURED *filesystem* I/O rates in excess of 10MB (yes, that is
>> megaBYTES/second) through this thing on a 5-disk array running RAID 5
>> doing *WRITES*.
>  Details?  I can get speeds up to 50MB/s with my DPT, but it doesn't mean
>it is representative of "normal" use.
>  RAID systems need to be optimized for your typical use.  On large
>sequentional writes, my current DPT controler only gets about 5MB/s, but
>it screams on random-access read-write.
>  PCI-SCSI RAID controllers are generally faster than SCSI-SCSI.  I'm sure
>that a DPT card would bury the CRD.
>  SCSI-to-SCSI controllers bring up the question of what SCSI card to use.
>The 2940UW is probably the fastest UW card, but the driver isn't very
>robust yet (maybe the CAM stuff is better).  The DPT driver has no such
>problems.  I've got two nearly identical servers, one with a 3940 and one
>with a DPT PM334.  The 3940 has a SCSI hang every 4 to 6 weeks.

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