Date: Tue, 22 Feb 2000 11:51:25 -0600 (CST) From: Joseph Thomas <jpt@networkcs.com> To: sos@freebsd.dk (Soren Schmidt) Cc: adsharma@sharmas.dhs.org (Arun Sharma), freebsd-current@FreeBSD.ORG Subject: Re: ABIT BP6, UDMA-66 and wdc AC310200 Message-ID: <200002221751.LAA70135@us.networkcs.com> In-Reply-To: <200002221730.SAA78748@freebsd.dk> from "Soren Schmidt" at Feb 22, 2000 06:30:21 PM
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> > It seems Arun Sharma wrote: > > > Do you have the prober 80pin cable ?? if so please provide a verbose boot... > > > > Thanks, that fixed the problem. Has anyone benchmarked the driver ? A very > > unscientific benchmark that I ran didn't seem to produce much of a difference > > between UDMA33 and UDMA66. In both cases, I got roughly 13 MB/s. > > There are almost no mesureable difference between UDMA33 and UDMA66, all > mesurements I've done (and have read about) sees little if no difference, > in fact some drives can be faster under UDMA33 even if they support the > higher rate too. > > > # dd if=/dev/ad4s2 of=/dev/null bs=40960k count=10 > > 10+0 records in > > 10+0 records out > > 419430400 bytes transferred in 30.797045 secs (13619177 bytes/sec) > > Thats probably close to what your drive can pull of the platters... > I get 22-23MB/sec off an IBM DPTA drive here with < 1% cpu usage, > so the driver is not the problem.. Look at your drive specs. I have one drive (Maxtor) with specs that say ~34MB to/from media and 66MB to/from interface (bus). Another piece of the puzzle is the amount of drive cache buffer. Again, I've seen between 512KB and 2MB. Mileage will vary... [It's the old 'burst rate of X' where the following 378 conditions must be met to reach the burst level...] > I have a config with 7 disks online, giving me a raw throughput > of ~100MB/s sustained, that is about the limit of what can be done > over the PCI bus... > > -Søren > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-current" in the body of the message > -- Joseph Thomas E/Mail: jpt@networkcs.com Network Computing Services, Inc. jpt@magic.net 1200 Washington Ave So. Tel: +1 612 337 3558 Minneapolis, MN 55415-1227 FAX: +1 612 337 3400 An elephant is a mouse with an operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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