From owner-freebsd-fs Mon Oct 5 11:02:53 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id LAA23239 for freebsd-fs-outgoing; Mon, 5 Oct 1998 11:02:53 -0700 (PDT) (envelope-from owner-freebsd-fs@FreeBSD.ORG) Received: from smtp01.primenet.com (smtp01.primenet.com [206.165.6.131]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id LAA23223 for ; Mon, 5 Oct 1998 11:02:48 -0700 (PDT) (envelope-from tlambert@usr01.primenet.com) Received: (from daemon@localhost) by smtp01.primenet.com (8.8.8/8.8.8) id LAA00353; Mon, 5 Oct 1998 11:02:19 -0700 (MST) Received: from usr01.primenet.com(206.165.6.201) via SMTP by smtp01.primenet.com, id smtpd000240; Mon Oct 5 11:02:06 1998 Received: (from tlambert@localhost) by usr01.primenet.com (8.8.5/8.8.5) id LAA21073; Mon, 5 Oct 1998 11:01:59 -0700 (MST) From: Terry Lambert Message-Id: <199810051801.LAA21073@usr01.primenet.com> Subject: Re: filesystem safety and SCSI disk write caching To: michaelh@cet.co.jp (Michael Hancock) Date: Mon, 5 Oct 1998 18:01:59 +0000 (GMT) Cc: eilts@tor.muc.de, freebsd-fs@FreeBSD.ORG In-Reply-To: from "Michael Hancock" at Oct 5, 98 10:48:11 am X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > > I can post (once again) the results of a Novell study on server usage > > > patterns. The 30,000 foot view for a typical server breaks down to: > > > > > > 75% reads > > > 15% writes > > > 8% directory search operations > > > 2% other > > > > How does this translate to disk usage? I think, VM/buffer cache will > > reduce reads and directory search operations quite a lot. > > No. Yes. The ratio of actual disk writes to disk reads is probably enough > to justify the effort to optimize writes. According to other postings in this thread, the empirical difference in wall time measured on the prototypical FreeBSD benchmark of "make world" is 5.6% between async + noatime vs. soft updates. While it would be worthwhile to attempt to optimize this further, I think doing so by enabling write caching is a cop-out. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message