Date: Mon, 2 Feb 1998 16:41:14 -0800 (PST) From: Tom <tom@uniserve.com> To: Karl Denninger <karl@mcs.net> Cc: current@FreeBSD.ORG Subject: Re: RAID controllers - folks, check this thing out Message-ID: <Pine.BSF.3.96.980202163524.13268K-100000@shell.uniserve.com> In-Reply-To: <19980130233604.57426@mcs.net>
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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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