From owner-freebsd-performance@FreeBSD.ORG Sun Oct 2 17:04:47 2005 Return-Path: X-Original-To: freebsd-performance@freebsd.org Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9E3E916A41F for ; Sun, 2 Oct 2005 17:04:47 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: from web30303.mail.mud.yahoo.com (web30303.mail.mud.yahoo.com [68.142.200.96]) by mx1.FreeBSD.org (Postfix) with SMTP id 378EB43D45 for ; Sun, 2 Oct 2005 17:04:47 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: (qmail 78676 invoked by uid 60001); 2 Oct 2005 17:04:46 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=Ie1Vqihmzx5zEt7vSyA3iyAVDpMVuzPoFEwmFHdoRACalN9qAKq+H1YfeCa/Tl8eyDU2x9c9rruqdMXzaP+pSFDJgPSDjJO0b4MiekYWmG4BpQDTcZCojw09xZCdMDPgoJO89MCvw+FIv8pdQAYOJxyISpgZzPHsVM6esD6/V0Q= ; Message-ID: <20051002170446.78674.qmail@web30303.mail.mud.yahoo.com> Received: from [213.54.70.142] by web30303.mail.mud.yahoo.com via HTTP; Sun, 02 Oct 2005 10:04:46 PDT Date: Sun, 2 Oct 2005 10:04:46 -0700 (PDT) From: Arne "Wörner" To: Patrick Proniewski In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: freebsd-performance@freebsd.org Subject: Re: dd(1) performance when copiing a disk to another X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 02 Oct 2005 17:04:47 -0000 Hi! --- Patrick Proniewski wrote: > > Can u find out, if DMA transfers are enabled for those discs? > > What does dmesg say? > > see end of mail for full dmesg output, > Looks good... :-)) But I never saw FBSD's kernel messages about SATA drives... ;-) > > Maybe atacontrol(8) says something useful about SATA discs, > > too (e. g. atacontrol mode 0)? > > # atacontrol mode 0 > Master = BIOSPIO > Slave = BIOSPIO > Hmm... 0 seems to be the wrong ata... Thats why the output does not fit to SATA drives, I think... > # dd if=/dev/ad4 of=/dev/null bs=1m count=1000 > 1000+0 records in > 1000+0 records out > 1048576000 bytes transferred in 17.647464 secs (59417943 > bytes/sec) > That seems to be 2 or about 2 times faster than disc->disc transfer... But still slower, than I would have expected... SATA150 sounds like the drive can do 150MB/sec... As far as I know, SATA busses are independant from each other (no master/slave; every drive gets its own cable)... Maybe "dd" cannot issue a read request, while the write isn't completed? DMA shouldn't be the problem, since the memory interface is quite fast in your case... So there remain the questions: 1. Why does the read speed drop in ur setting (maybe writing to ad6 takes more time than reading from ad4? u could try to run two dd processes one with if=ad4 and the other with if=ad6)? 2. Why can't we reach 150MB/sec? > > (Maybe you could find a way to copy /dev/zero to /dev/ad6 > > without destroying the previous work... :-)) > > well, not very easy both disk are the same size ;) > I thought of the first 1000 1MB blocks... :-) The write speed might be interesting... -Arne __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com