From owner-freebsd-questions@FreeBSD.ORG Tue Mar 15 22:11:08 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D5EFC1065676 for ; Tue, 15 Mar 2011 22:11:08 +0000 (UTC) (envelope-from amvandemore@gmail.com) Received: from mail-fx0-f54.google.com (mail-fx0-f54.google.com [209.85.161.54]) by mx1.freebsd.org (Postfix) with ESMTP id 654698FC15 for ; Tue, 15 Mar 2011 22:11:08 +0000 (UTC) Received: by fxm11 with SMTP id 11so1243987fxm.13 for ; Tue, 15 Mar 2011 15:11:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=Pf8t1VtP2CdICU/T3kJz2OHBvX8sX+ITdk5qylDBLkQ=; b=VsNQkSqPQKrJ9cv5F5nzVlUN4wreIFpXTnaShuxyE0ZElkAjSbZnWnQgOKlNfVKCy8 4EKaYQlYE3pgppiExoquT2oJmaqBFzDFH0wohKiOpMUmSTof/kbAfpR9ErLSo+J/P7oy TLF89Avtgn8TdCarliDx+sWR8JNuWAthE8XsU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=TWG8D8U9UhPEkNb8DLIt41/16Y7Zc2kyreaDUEal+iVojxb2/kXm5PHgWbsxaVa3mF DJ72RTebvH+D2V4EpdRZn1y8rgpYtwexkEhRS6dnqvKcH2OK6y1y0HsTuRtePtLZ3rE0 QZ+Qw9PpXiZiEMyzU1p9uZrEp9t424XPN3PVE= MIME-Version: 1.0 Received: by 10.223.6.11 with SMTP id 11mr45955fax.99.1300226840568; Tue, 15 Mar 2011 15:07:20 -0700 (PDT) Received: by 10.223.59.7 with HTTP; Tue, 15 Mar 2011 15:07:20 -0700 (PDT) In-Reply-To: <20110315215907.f8a08352.freebsd@edvax.de> References: <8a6023db5a3d4c8b34161f7ee0af29bb.squirrel@wtp1.ath.cx> <201103151041.56373.erich@alogreentechnologies.com> <5ab7e13805185464a4adf0c5d326671e.squirrel@wtp1.ath.cx> <20110315215907.f8a08352.freebsd@edvax.de> Date: Tue, 15 Mar 2011 17:07:20 -0500 Message-ID: From: Adam Vande More To: Polytropon Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd_user@guice.ath.cx, freebsd-questions@freebsd.org Subject: Re: IDE -- mount partitions for better performance X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Mar 2011 22:11:09 -0000 On Tue, Mar 15, 2011 at 3:59 PM, Polytropon wrote: > Keep in mind that performance "across" ad0 and ad2 is best. > Masters are always good. Slaves are slower. Using primary > and secondary in parallel works good, working on a master > and a slave simultanously is worse. > Your statement about master being faster than a slave is simply not true for almost every scenario when using devices with same capabilites. All master/slave really controls is enumeration, and shouldn't effect performance in and of itself. Other variables can effect that of course, like using a slower device as an ATA Device-1 with a faster Device-0. Even that example isn't ubiquitous as many, maybe most controllers are able to support mixed devices each in their fastest mode. The whole IDE device contention really isn't much of a bottle neck in this scenario. It's only a big factor when there's *a lot* of simultaneous IO going to both, say dumping one disk to another. The highest preforming setup in something like this is likely to be something along the lines of a 4-way /boot gmirror, and a 4-way gstripe with a smaller stripe size eg 32k across the remaining usable space. If you aggregate your disk IO in this manner, IDE channel contention shouldn't be much of a bottleneck. -- Adam Vande More