Date: Fri, 17 Dec 1999 12:02:54 -0800 From: Mike Smith <msmith@freebsd.org> To: David Gilbert <dgilbert@velocet.ca> Cc: freebsd-current@freebsd.org Subject: Re: AMI MegaRAID datapoint. Message-ID: <199912172002.MAA00660@mass.cdrom.com> In-Reply-To: Your message of "Fri, 17 Dec 1999 10:02:57 EST." <14426.20641.329657.464545@trooper.velocet.net>
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> >>>>> "Mike" == Mike Smith <msmith@freebsd.org> writes: > > >> The AMI MegaRAID 1400 delivers between 16.5 and 19 M/s (the 19M/s > >> value is somewhat contrived --- using 8 bonnies in parrallel and > >> then summing their results --- which is not 100% valid)... but the > >> MegaRAID appears to be stable. > > Mike> Hmm. Those numbers aren't so great though. I'd be interested > Mike> to know how busy the controller is during your test (use systat > Mike> -vmstat 1 and look at the amrd0 device), as well as how you've > Mike> configured it. AMI's default configurations for those > Mike> controllers is wildly inconsistent between one BIOS version and > Mike> the next. > > Well... it's RAID-5 across the same 8 drives with all 8 drives on one > LVD chain (same configuration as the other test). I have tried the > 128k stripe, but it was slower than the default 64k stripe. Try enabling DirectIO and WriteBack if you haven't already. AMI's RAID5 implementation seems to suffer from rewriting the entire stripe when you do sub-stripe-sized writes, but I'm not sure about that yet. The Mylex controllers seem to have a small edge in performance, which may be due to them doing cache-line-sized I/Os (usually only 8k) in that case. -- \\ Give a man a fish, and you feed him for a day. \\ Mike Smith \\ Tell him he should learn how to fish himself, \\ msmith@freebsd.org \\ and he'll hate you for a lifetime. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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