From owner-freebsd-questions Mon Aug 26 14: 0:42 2002 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 386D137B401 for ; Mon, 26 Aug 2002 14:00:38 -0700 (PDT) Received: from mailsrv.otenet.gr (mailsrv.otenet.gr [195.170.0.5]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5C95643E6A for ; Mon, 26 Aug 2002 14:00:36 -0700 (PDT) (envelope-from keramida@ceid.upatras.gr) Received: from hades.hell.gr (patr530-a193.otenet.gr [212.205.215.193]) by mailsrv.otenet.gr (8.12.4/8.12.4) with ESMTP id g7QL0WpD013306; Tue, 27 Aug 2002 00:00:33 +0300 (EEST) Received: from hades.hell.gr (hades [127.0.0.1]) by hades.hell.gr (8.12.5/8.12.5) with ESMTP id g7QL0USi007631; Tue, 27 Aug 2002 00:00:30 +0300 (EEST) (envelope-from keramida@ceid.upatras.gr) Received: (from charon@localhost) by hades.hell.gr (8.12.5/8.12.5/Submit) id g7QL0T33007629; Tue, 27 Aug 2002 00:00:29 +0300 (EEST) (envelope-from keramida@ceid.upatras.gr) Date: Tue, 27 Aug 2002 00:00:29 +0300 From: Giorgos Keramidas To: Chris Ptacek Cc: "'David Schultz'" , Carlos Carnero , freebsd-questions@FreeBSD.ORG Subject: Re: optimization changed from TIME to SPACE ?! Message-ID: <20020826210028.GB6243@hades.hell.gr> References: <31269226357BD211979E00A0C9866DAB02BB998B@rios.sitaranetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <31269226357BD211979E00A0C9866DAB02BB998B@rios.sitaranetworks.com> X-PGP-Fingerprint: C1EB 0653 DB8B A557 3829 00F9 D60F 941A 3186 03B6 X-Phone: +30-944-116520 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 On 2002-08-26 15:02 +0000, Chris Ptacek wrote: > I had a few questions... What actually causes the fragmentation to > occur? I have tried just copying a small file over and over and > this results in no fragmentation. This leads me to believe that the > fragmentation is a result of simultainious open files or at least > different file sizes. The way that the FreeBSD filesystem organises data on disk. This "fragmentation" is not the same as fragmentation on a DOS partition, if this is what had you confused. > Also it seems that when we switch to SPACE optimizaiton is based on > the % fragmentation based on the minfree setting. Can I change the > minfree for the filesystem (I have a dedicated cache partition) to > like 27% (8 is default) so that I am much less likely to hit the > SPACE case? Then the SPACE optimization will start when 3 times more space is taken by fragments. But this is going to reserve 27% of the disk space for the superuser and block allocation routines. This is too much disk space to reserve :/ A better solution is probably to format the partition with a fragment size equal to the block size as someone mentioned. I haven't tried this though and I can't say how much it affects performance and why. -- FreeBSD: The Power to Serve <> http://www.FreeBSD.org FreeBSD 5.0-CURRENT #0: Wed Aug 21 22:08:19 EEST 2002 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message