Date: Wed, 25 Jul 2007 21:14:40 -0400 From: Howard Goldstein <hg@queue.to> To: Scott Long <scottl@samsco.org> Cc: freebsd-stable@freebsd.org Subject: Re: [resolved, naively] Re: geom vs ich through ar device - benchmarks? Message-ID: <46A7F580.6000005@queue.to> In-Reply-To: <46A7F2C2.2090009@samsco.org> References: <46A4E8FA.6010403@queue.to> <46A7B3FB.7010504@queue.to> <46A7B7AF.6080308@samsco.org> <46A7BF8C.5020909@queue.to> <46A7F2C2.2090009@samsco.org>
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Scott Long wrote: > Howard Goldstein wrote: > >> Scott Long wrote: >> >>> Howard Goldstein wrote: >>> >>>> Testbed: Pair of WDC3200AAKS 320gb SATA, freshly newfsd 10gb filesystem >>>> mounted with softupdates, remounted after each test >>>> P4 @ 3ghz on a P4P800 in 6.2-STABLE, single user mode, ICH5R controller >>>> detects these SATA-II drives inexplicably as SATA-I >>>> >>>> >>> ICH5 only support SATA-1. >>> >> Dang. Does anyone yield SATA-II speeds with the a PCI controller? I'm >> not sure if 25-30MB/s is even possible with regular PCI >> >> > > Even PCI-33 should be able to sustain about 100MB/s, enough to handle a > single disk drive. Many controller are PCI-X or PCIe now, which has > plenty of bandwidth for 4-8 drives. > > Sorry I dropped a zero as my stupid test showed 76-77MB/s. I think I should perhaps throw in the towel as the manual for this old P4P800 claims its "32 bit PCI 2.2 support ... 133MB/s maximum" >>>> 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. >>> >>> >> It's helpful - thank you. Do you think I'm correct in assuming the >> interface is pretty much saturated at this point and if I wanted >> additional speed I'd need to start thinking bringing in additional or >> faster interfaces? >> > > You should be able to sustain at least 70MB/s on a single modern drive > with SATA-1 or SATA-2. If you're not getting that then something in the > driver or the application is getting in the way. Even with the, um, > "problems" that SiI controllers are famous for, you should be able to > sustain a decent data rate on a single drive. > Thank you, Scott
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