From owner-freebsd-geom@FreeBSD.ORG Wed Dec 31 03:41:35 2008 Return-Path: Delivered-To: freebsd-geom@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 034561065670 for ; Wed, 31 Dec 2008 03:41:35 +0000 (UTC) (envelope-from jjacobson@panasas.com) Received: from laguna.int.panasas.com (gw-ca.panasas.com [66.104.249.162]) by mx1.freebsd.org (Postfix) with ESMTP id DF9AC8FC12 for ; Wed, 31 Dec 2008 03:41:34 +0000 (UTC) (envelope-from jjacobson@panasas.com) Received: from [172.17.133.160] ([172.17.133.160]) by laguna.int.panasas.com with Microsoft SMTPSVC(6.0.3790.3959); Tue, 30 Dec 2008 19:29:16 -0800 Message-Id: <4AD370A6-2226-442F-BD80-8CFD4045B094@panasas.com> From: Joel Jacobson To: freebsd-geom@freebsd.org Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v929.2) Date: Tue, 30 Dec 2008 19:29:20 -0800 X-Mailer: Apple Mail (2.929.2) X-OriginalArrivalTime: 31 Dec 2008 03:29:16.0965 (UTC) FILETIME=[F5C64D50:01C96AF7] Subject: performance problem with gstripe X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 31 Dec 2008 03:41:35 -0000 i have a bit of a weird issue, which i suspect is a configuration problem, and was looking for a little advice. i have an LSI JBOD box with a bunch of SAS drives that i would like to gstripe together. each drive individually seems to be able to do about 80 MB/sec streaming write, and doing parallel dd's gives me the 160 MB/sec i would expect. if i gstripe them together with a 256k stripe width, i only see 80 MB/sec, though. if, however, i newfs/mount it as ufs and then dd myself a big file, that gets me about 120-130 MB/sec. why does mounting matter? - j