Date: Wed, 4 Mar 2009 20:38:52 +0100 (CET) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-hackers@FreeBSD.ORG, octavian.covalschi@gmail.com Subject: Re: Spin down HDD after disk sync or before power off Message-ID: <200903041938.n24Jcqdr060153@lurza.secnetix.de> In-Reply-To: <c0f49ea0903040910w496f4a72m3c3ce6882e55c307@mail.gmail.com>
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Octavian Covalschi wrote: > I'm looking a way to spin down HDD just right before power off. Why? > > Because currently when I call "shutdown -p now", HDD is powered off at it's > full speed (7200.4) and as a result > I hear a noise of stopping/spinning down of HDD, and _this_ concerns me as > I'm afraid it can damage HDD. You don't have to spin down a disk before powering it off. The noise you hear is probably caused by the "autopark" feature of the drive. It is harmless. > I've tried to use rc.shutdown, but the sync of disks "wakes" HDD again... Of course, upon halt or reboot the kernel will sync all file systems that have been mounted read+write. > While searching for a solution, I noticed that reboot command/app _does_ > spin down hdd right before it resets system power, > I can hear how HDD is powered on after that... No, the reboot command doesn't do that. It's probably your BIOS that resets the devices. > 2nd thing is I cannot find "halt.c" file, i wanted to take a look how it > does it... although I'm up to date it's not not in > /usr/src/sbin halt(8) is a hardlink to reboot(8). Look at src/sbin/reboot. By the way, the syncing does not happen in halt(8). At the time the kernel syncs the disks, no processes are running anymore, not even init(8). You can't do anything from userland at this point. If you want to insert a spin-down for your disks, you will have to modify the kernel. You have to install an event handler for "shutdown_post_sync". See the boot() function in src/sys/kern/kern_shutdown.c for details about the kernel's shutdown sequence. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "Python is an experiment in how much freedom programmers need. Too much freedom and nobody can read another's code; too little and expressiveness is endangered." -- Guido van Rossum
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