Date: Thu, 26 Jul 2007 12:34:48 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-stable@FreeBSD.ORG, scottl@samsco.org, hg@queue.to Subject: Re: [resolved, ?naively] Re: geom vs ich through ar device - benchmarks? Message-ID: <200707261034.l6QAYm7u001453@lurza.secnetix.de> In-Reply-To: <46A7B7AF.6080308@samsco.org>
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Scott Long wrote: > Howard Goldstein wrote: > > Naive test: dd if=/dev/zero of=/fsundertest/tstfile bs=1m count=1000 > > *not including buffered stuff unwritten, the test simply reported dd's > > idea of the transfer time*, and then the other way where it doesn't matter > > > > In firmware's RAID1 Using the awesome gmirror > > write 1gb: 13.275 13.7 > > rd 12.9 13.8 > > > > Of course after this I used gmirror... > > Just so we're clear, the ICH5 doesn't have any firmware and doesn't > actually do any RAID operations. What is has is hook into the system > BIOS during boot. That hook allows the BIOS to do RAID-like operations > during boot, until the OS takes over control of the devices. After > that, it's up to the OS to do all the RAID work. The 'ar' driver is > still software RAID, just like gmirror. What you've effectively done > merely compare the performance of one software RAID stack to another. > That's certainly an interesting comparison, but maybe not exactly what > you had in mind. As an additional note: _If_ the ICH RAID was in hardware (which it isn't, as Scott pointed out), it might be preferable to use it instead of gmirror, even if it's 5% slower, but because it would save a lot of cpu. Of course, since both are in software and probably consume similar amounts of cpu, it's better to use gmirror because it's a little faster. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "C++ is the only current language making COBOL look good." -- Bertrand Meyer
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