From owner-freebsd-questions@FreeBSD.ORG Mon Nov 22 17:12:56 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 51C4B16A4CE for ; Mon, 22 Nov 2004 17:12:56 +0000 (GMT) Received: from smtpout.mac.com (smtpout.mac.com [17.250.248.44]) by mx1.FreeBSD.org (Postfix) with ESMTP id F0F4743D5A for ; Mon, 22 Nov 2004 17:12:55 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from mac.com (smtpin07-en2 [10.13.10.152]) by smtpout.mac.com (8.12.6/MantshX 2.0) with ESMTP id iAMHCtOo029284 for ; Mon, 22 Nov 2004 09:12:55 -0800 (PST) Received: from [10.1.1.245] (nfw2.codefab.com [199.103.21.225] (may be forged)) (authenticated bits=0) by mac.com (Xserve/smtpin07/MantshX 4.0) with ESMTP id iAMHCrHE002519 for ; Mon, 22 Nov 2004 09:12:55 -0800 (PST) Mime-Version: 1.0 (Apple Message framework v619) In-Reply-To: <20041121191737.GA2270@gicco.homeip.net> References: <20041121093347.GA861@gicco.homeip.net> <41A0B955.8090700@mac.com> <20041121191737.GA2270@gicco.homeip.net> Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: Charles Swiger Date: Mon, 22 Nov 2004 12:12:52 -0500 To: freebsd-questions@freebsd.org X-Mailer: Apple Mail (2.619) Subject: Re: Tracing Disk Activity 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, 22 Nov 2004 17:12:56 -0000 On Nov 21, 2004, at 2:17 PM, Hanspeter Roth wrote: > On Nov 21 at 10:50, Chuck Swiger spoke: >> Hanspeter Roth wrote: >>> I have set an idle timeout for the hard-disk. But when there is no >>> user activity there are frequent disk accesses. >> >> Yes, this is Unix. Even when there is no user activity, a Unix system >> normally is still running a number of daemons such as syslogd which >> regularly write to the filesystem. Beyond that, the syncer mechanism >> tries >> to reduce the number of dirty memory buffers every thirty seconds or >> so. > > I guess that some daemons are causing disk access. But it must be > not only syslogd. That's right. Normally, people end up running a number of daemons like sendmail or some other MTA, ntpd, named, etc. > Is the syncer causing the disk to spin up even if there is nothing to > flush? Probably no. However, if you have active processes running on the system, it is very likely that the syncer will find data that it does want to write. > [...] >> Instead you probably will need to mount filesystems read-only and >> create >> RAM disks in a fashion similar to booting off limited-write media like > > My idea is to transfer those files that are written also when the > user is idle to a RAM disk (some from /var/log and dhclient.leases). > But I don't want to mount the filesystems read-only. OK. However, you are probably not going to be able to prevent everything running on a normal Unix system that wants to scribble to disk short of heroic measures. >> Compact Flash. Either that, or simply shutdown the system or run zzz >> to >> suspend the system via APM/APCI. > > This is less convenient and probably doesn't work on my laptop. (I > have to check whether the upgrade to 5.3R has changed something in > this respect.) Hmm. For what it is worth, it's taken about two years of effort by Apple to work through many of these issues in order to get MacOS X on their laptops to be reasonably friendly in terms of saving power, conserving hard drive access, and having power save/suspend to RAM behave properly. -- -Chuck