Date: Tue, 4 Sep 2001 08:32:42 -0400 From: David Gilbert <dgilbert@velocet.ca> To: Greg Lehey <grog@FreeBSD.org> Cc: Chris BeHanna <behanna@zbzoom.net>, FreeBSD-Stable <stable@FreeBSD.org> Subject: [stable] Re: RAID5 Message-ID: <15252.51690.121158.427612@trooper.velocet.net> In-Reply-To: <20010904105035.C10292@wantadilla.lemis.com> References: <030201c1349b$a0c254b0$2aa8a8c0@melim.com.br> <20010903141721.D10812-100000@topperwein.dyndns.org> <20010904105035.C10292@wantadilla.lemis.com>
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>>>>> "Greg" == Greg Lehey <grog@FreeBSD.org> writes: Greg> On Monday, 3 September 2001 at 14:20:56 -0400, Chris BeHanna Greg> wrote: >> FWIW, I set up a 4-drive RAID-5 volume with an associated >> journaling device on Solaris 8 that performs pretty well for home >> directories. I wouldn't expect vinum to be any different in that >> regard, given sufficient CPU (my Solaris volume is served from a >> two-CPU E450, just as a reference point). Greg> Interestingly, CPU isn't the performance issue most people Greg> (myself once included) assume it is. Even on my original Vinum Greg> testbed, a 468/66, CPU usage was barely measurable. That's Greg> probably why most hardware RAID controllers use relatively slow Greg> CPUs. Well... then its an interesting issue: At least on FreeBSD, my benchmarks show that Vinum running with Adaptec (ahc) or TekRAM (sym) controllers outperform hardware raid controllers significantly. We're talking same drives, same cables, same computer here. Not only does Vinum outperform hardware RAID 5, but it also outperforms hardware RAID 0 and RAID 1. Now... these are all FreeBSD tests. Maybe the FreeBSD hardware raid controller drivers suck? As an example (numbers I have readily available), my test bed was 8x 18G Atlas IV drives (SCA if it matters) in a dedicated LVD case. I was testing the AMI MegaRAID 1500 against Vinum running with either an Adaptec 29160 or a TekRAM (forget model number, but it was LVD-80 not LVD-160). I found that write speeds were pretty much even all around... with a slight edge to Vinum --- 4M/s writes on the AMI, 4.5M/s writes on Vinum. Reading, however, is where vinum dusted the competition. On either SCSI controller, Vinum could achieve 51M/s reads compared to 18M/s reads on the AMI. Interestingly, the figure for vinum changes with CPU speed --- it was only 38M/s reads with a PIII/450 (100Mhz RAM) ... the 51M/s measurement was an Athlon 750 (133Mhz RAM). Dave. -- ============================================================================ |David Gilbert, Velocet Communications. | Two things can only be | |Mail: dgilbert@velocet.net | equal if and only if they | |http://www.velocet.net/~dgilbert | are precisely opposite. | =========================================================GLO================ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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