Date: Tue, 3 Feb 1998 08:42:45 +0100 From: "Alex Chircop" <alex.j.chircop@magnet.mt> To: "Tom" <tom@uniserve.com> Cc: <current@FreeBSD.ORG> Subject: Re: RAID controllers - folks, check this thing out Message-ID: <000001bd3081$a38a34a0$280e0181@magnet.mt>
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What drivers are you using for the DPT controllers ? Regards, Alex -----Original Message----- From: Tom <tom@uniserve.com> To: Karl Denninger <karl@mcs.net> 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 cache >> memory, and also has battery backup capabilities (attach a 6V Gelcel to it). > > Just a standard SCSI-to-SCSI RAID device. These have been around for >years. DEC, Mylex, and others have been making them for some >time. > >> 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. > >Tom >
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