Date: Wed, 05 Apr 2000 20:07:26 -0600 From: "Justin T. Gibbs" <gibbs@FreeBSD.org> To: mjacob@feral.com Cc: Andrew Heybey <ath@niksun.com>, freebsd-bugs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: kern/17153 (was: newfs on IBM disks slower than Seagate disks?) Message-ID: <200004060207.UAA24407@caspian.plutotech.com> In-Reply-To: Your message of "Wed, 05 Apr 2000 18:59:28 PDT." <Pine.BSF.4.10.10004051855221.7415-100000@beppo.feral.com>
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>> Newfs of a ~16GB partition (as performed by sysinstall, so the newfs >> arguments are the same) is *much* slower on IBM 18GB 10K RPM LVD disks >> versus similar Seagates. Systems are otherwise identical (same >> controller (onboard Adaptec AIC7896), same motherboard, same amount of >> RAM). Once newfs'd, bonnie and iozone give similar performance for >> the two disks. Rawio also gives similar numbers for the two. >> >> Running 3.2-RELEASE. >> >> IBM disks are DMVS18V. >> Seagates are Cheetah ST318203LW. >> >> Why would this be the case? IBM usually ships with the write cache disabled. Seagate almost always has it enabled. As newfs is a "single blocking I/O at a time" kind of application, the additional write latency causes a degradation in performance. When going through the filesystem, this latency is hidden by the buffer cache. You can view mode page 8 with camcontrol to determine the settings for your drives. Man camcontrol for details. -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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