From owner-freebsd-geom@FreeBSD.ORG Sat Nov 4 22:09:19 2006 Return-Path: X-Original-To: freebsd-geom@freebsd.org Delivered-To: freebsd-geom@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id EC72C16A4A7 for ; Sat, 4 Nov 2006 22:09:19 +0000 (UTC) (envelope-from don_oles@able.com.ua) Received: from able.com.ua (able.com.ua [80.91.162.66]) by mx1.FreeBSD.org (Postfix) with ESMTP id CE8B743D60 for ; Sat, 4 Nov 2006 22:09:17 +0000 (GMT) (envelope-from don_oles@able.com.ua) Received: from able.com.ua (localhost [127.0.0.1]) by able.com.ua (Postfix) with ESMTP id 3908644C2D for ; Sun, 5 Nov 2006 00:09:10 +0200 (EET) Received: from vanta.oles.net (ip.85.202.111.30.dyn.sub-1.broadband.voliacable.com [85.202.111.30]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by able.com.ua (Postfix) with ESMTP id D1F1644C29 for ; Sun, 5 Nov 2006 00:09:09 +0200 (EET) Date: Sun, 5 Nov 2006 00:09:19 +0200 From: Oles Hnatkevych X-Mailer: The Bat! (v3.71.01) Professional X-Priority: 3 (Normal) Message-ID: <961295086.20061105000919@able.com.ua> To: freebsd-geom@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV using ClamSMTP at ABLE Subject: geom stripe perfomance question X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Oles Hnatkevych List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Nov 2006 22:09:20 -0000 Hello all! I wonder why geom stripe works much worse than the separate disks that constitute stripe. I have a stripe from two disks. Disks are on separate ATA channels. root# gstripe list Geom name: bigdata State: UP Status: Total=2, Online=2 Type: AUTOMATIC Stripesize: 262144 ID: 4233231544 Providers: 1. Name: stripe/bigdata Mediasize: 500118323200 (466G) Sectorsize: 512 Mode: r1w1e1 Consumers: 1. Name: ad1 Mediasize: 250059350016 (233G) Sectorsize: 512 Mode: r1w1e2 Number: 0 2. Name: ad2 Mediasize: 250059350016 (233G) Sectorsize: 512 Mode: r1w1e2 Number: 1 Now let's read one of them and stripe. root# dd if=/dev/ad1 of=/dev/null bs=1m count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 14.579483 secs (71921343 bytes/sec) root# dd if=/dev/stripe/bigdata of=/dev/null bs=1m count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 15.882796 secs (66019610 bytes/sec) What I would expect is doubling the speed of transfer, not slowing down. Am I wrong? Or is geom_stripe inefficient? I tried to do the same with gvinum/stripe - the read speed was degraded too. And with gmirror depending on slice size speed was degraded differently. I am running 6.2-PRERELEASE on Celeron 800. -- Oles Hnatkevych mailto:don_oles@able.com.ua