From owner-freebsd-questions Thu Aug 9 21:54:21 2001 Delivered-To: freebsd-questions@freebsd.org Received: from yonge.cs.toronto.edu (yonge.cs.toronto.edu [128.100.1.8]) by hub.freebsd.org (Postfix) with SMTP id D96F337B403 for ; Thu, 9 Aug 2001 21:54:16 -0700 (PDT) (envelope-from khui@cs.toronto.edu) Received: from gerrard ([128.100.3.242]) by yonge.cs.toronto.edu with SMTP id <33964-21682>; Fri, 10 Aug 2001 00:54:14 -0400 Message-ID: <007001c12158$b2ee87e0$07010101@mtwx1.on.home.com> From: "Kevin Hui - DCS" To: "Alfred Perlstein" Cc: References: <20010809190350.M85642@elvis.mu.org> Subject: Re: Experiencing very slow raw write speeds on /dev/ad1 Date: Fri, 10 Aug 2001 00:55:36 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Thank you, Alfred, for the hint. Adding write caching helped a lot. Now the write speed jumps to ~15.8MB/s instead of the previous 3.5MB/s. Are there any other such settings I should pay attention to? I asked because I believe that the performance is still not as good as can be. I have the rawio program running under Linux with the identical hardware (accessing the /dev/raw/raw0, which maps to /dev/hdb) and I got ~38.4MB/s raw write speed (BTW I get ~38.4MB/s from both Linux and FreeBSD when I do the single-process raw sequential read test). Thanks, -Kevin. ----- Original Message ----- From: "Alfred Perlstein" To: "Kevin Hui" Cc: Sent: Thursday, August 09, 2001 8:03 PM Subject: Re: Experiencing very slow raw write speeds on /dev/ad1 > * Kevin Hui [010809 18:10] wrote: > > Hi all, > > > > I have installed 2 Maxtor UDMA100 drives in my system, sharing the channel > > ide0. /dev/ad0 contains all the FreeBSD partitions and ad1 is used as a > > scratch drive (there's nothing on it). Ide1 channel is used for the DVD > > drive (which doesn't support UDMA): > > FreeBSD 4.3 was released with IDE write caching turned off. This > was to help people preserve thier data, but since most IDE disks > perform so badly with it off it's back on in recent FreeBSD versions. > > You can also turn it on by adding the line: > hw.ata.wc=1 > to your /boot/loader.conf > > and please don't cc multiple lists when asking a question. > > -Alfred > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message