From owner-freebsd-questions@FreeBSD.ORG Mon Jun 7 18:34:24 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 84A2416A4CE for ; Mon, 7 Jun 2004 18:34:24 +0000 (GMT) Received: from smtp.owt.com (smtp.owt.com [204.118.6.19]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1F3F043D55 for ; Mon, 7 Jun 2004 18:34:24 +0000 (GMT) (envelope-from kstewart@owt.com) Received: from [207.41.94.233] (owt-207-41-94-233.owt.com [207.41.94.233]) by smtp.owt.com (8.12.8/8.12.8) with ESMTP id i57IXTbI028497; Mon, 7 Jun 2004 11:33:31 -0700 From: Kent Stewart To: freebsd-questions@freebsd.org Date: Mon, 7 Jun 2004 11:34:17 -0700 User-Agent: KMail/1.6.2 References: <20040606233406.GA485@lori.mine.nu> <40C3F8E2.5010203@mac.com> In-Reply-To: <40C3F8E2.5010203@mac.com> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message-Id: <200406071134.17742.kstewart@owt.com> cc: Geert Hendrickx Subject: Re: suggestions for optimal filesystem-layout over multiple harddrives? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Jun 2004 18:34:24 -0000 On Sunday 06 June 2004 10:10 pm, Chuck Swiger wrote: > Geert Hendrickx wrote: > > using multiple harddisks can increase performance, since I/O can be > > done in parallel. But what would be an optimal filesystem-layout > > on, say, two disks of equal size? Swap should evidently be spread > > equally over the different drives. As for the filesystems, say I'd > > have a large /usr and /home, each on one harddrive, and smaller /, > > /var and /tmp which could reside on either disk. / and /usr would > > be mostly read-only. > > There is nothing wrong with the approach you are taking, and it will > indeed help balance load out between multiple spindles. That being > said, you have to know (by measuring) or at least predict what your > I/O access patterns are between the various filesystems in order to > gain full advantage. > > An easier way of balancing load between two or more drives involves > using RAID-0 striping, although the drives do not have to be equal in > size. Commodity ATA RAID controllers like Highpoint, Promise, & 3ware > are fairly cheap, or one could use software RAID like vinum. I was worried about buildworld speed and found I could optimize for that=20 very easy. You need 3 HDs on their own controller and create mount=20 points for /usr/src and /usr/obj on the 2nd and 3rd controller. Since=20 the HDs are so large, I also created a mount point for /usr/ports on=20 one of those other controllers. You only see 10-15% faster build times=20 when you do this and it is a question of how long you are going to run=20 your system before you are paid back for the time you spent worrying=20 about it. =46rom my days of benchmarking supercomputers, we found it was always easy= =20 to move files produced by users onto a different set of HDs than the=20 system was using. You separated the files the system wanted quick=20 access to from the files being produced by users. The programs we ran=20 generated a lot of data and disk caching was much more important than=20 location of the files. What becomes important with caching is whether=20 fast access to files you want to read is most important or data=20 integrity. If data integrity is not important because you are going to=20 restart the program and run it from scratch, then write behind caching=20 is easy to setup.=20 I haven't encountered any environment like that since I retired.=20 My /home/user accounts are all on /usr. Kent =2D-=20 Kent Stewart Richland, WA http://users.owt.com/kstewart/index.html