From owner-freebsd-scsi Fri Oct 8 0: 3:43 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by hub.freebsd.org (Postfix) with ESMTP id A151514DC5 for ; Fri, 8 Oct 1999 00:03:38 -0700 (PDT) (envelope-from grog@freebie.lemis.com) Received: (from grog@localhost) by freebie.lemis.com (8.9.3/8.9.0) id QAA97636; Fri, 8 Oct 1999 16:33:16 +0930 (CST) Date: Fri, 8 Oct 1999 16:33:16 +0930 From: Greg Lehey To: Tom Cc: The Hermit Hacker , freebsd-scsi@FreeBSD.ORG Subject: Re: DPT Controller options ... one question Message-ID: <19991008163316.E78191@freebie.lemis.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0pre2i In-Reply-To: WWW-Home-Page: http://www.lemis.com/~grog X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Thursday, 7 October 1999 at 19:39:50 -0700, Tom wrote: > > On Fri, 8 Oct 1999, The Hermit Hacker wrote: > >> >> Okay, thanks... >> >> If there are cache's on the DPT controllers, does the OS make use of >> that, or is it automagic and transparent to the OS? Just want to make >> sure I'm getting full use of these things... >> >> Thanks... > > The onboard cache is transparent to the host. Howerver, there are many > settings available for tuning it though. You can set things like delay > before writing, and maximum amount of cache that can be "dirty" before a > flush is forced. Regardless, DPT IV cards are optimized for random > access. My DPT IV card never benchmarked well, but on a mail server, it > always exceeded my expectations. The general consensus is that the DPT IV is a very poor performer. Mike Smith has just committed drivers for AMI and Mylex controllers, which work a little better. So far nobody has been overwhelmed by the performance of any of them. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message