From owner-freebsd-current@FreeBSD.ORG Sun Jan 3 22:44:25 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 094F3106568B for ; Sun, 3 Jan 2010 22:44:25 +0000 (UTC) (envelope-from peterjeremy@acm.org) Received: from mail12.syd.optusnet.com.au (mail12.syd.optusnet.com.au [211.29.132.193]) by mx1.freebsd.org (Postfix) with ESMTP id 8B4978FC12 for ; Sun, 3 Jan 2010 22:44:24 +0000 (UTC) Received: from server.vk2pj.dyndns.org (c122-106-232-83.belrs3.nsw.optusnet.com.au [122.106.232.83]) by mail12.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id o03MiLBg029905 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 4 Jan 2010 09:44:22 +1100 X-Bogosity: Ham, spamicity=0.000000 Received: from server.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by server.vk2pj.dyndns.org (8.14.3/8.14.3) with ESMTP id o03Mi86l030901; Mon, 4 Jan 2010 09:44:08 +1100 (EST) (envelope-from peter@server.vk2pj.dyndns.org) Received: (from peter@localhost) by server.vk2pj.dyndns.org (8.14.3/8.14.3/Submit) id o03Mi7bW030897; Mon, 4 Jan 2010 09:44:08 +1100 (EST) (envelope-from peter) Date: Mon, 4 Jan 2010 09:44:07 +1100 From: Peter Jeremy To: Aristedes Maniatis Message-ID: <20100103224407.GB76049@server.vk2pj.dyndns.org> References: <4AC141B0.4090705@delphij.net> <4B405C3D.7090501@ish.com.au> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="4bRzO86E/ozDv8r1" Content-Disposition: inline In-Reply-To: <4B405C3D.7090501@ish.com.au> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.20 (2009-06-14) Cc: freebsd-current@freebsd.org Subject: Re: [PATCH] Shutdown cooloff feature X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Jan 2010 22:44:25 -0000 --4bRzO86E/ozDv8r1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2010-Jan-03 19:58:37 +1100, Aristedes Maniatis wrote: >Why would an operating system have an unclean shutdown command at all? There are several different levels of "cleanliness": - "shutdown" optionally provides users with a warning of impending outage, cleanly stops applications then does "reboot" or similar. - "reboot" kills any running processes and then calls reboot(2) - reboot(2) sync's filesystems and physically reboots the host. In general, you should use "shutdown" because this ensures that everything is cleanly stopped. But there are cases where this isn't applicable: - On old Unix systems, you generally have to reboot without syncing disks if you need to fsck the root filesystem - Wedged applications might refuse to shutdown cleanly (especially on Solaris, a wedged application can wedge the entire shutdown process and require use of uadmin(1M) to reboot). OTOH, failing to shutdown cleanly can leave NFS servers thinking clients have filesystems mounted. And I've found that just rebooting my Sun SB1500 crashes the associated switch port (so I need to reboot my switch to recover) - I have no idea how it does this but both FreeBSD and OpenSolaris do it. --=20 Peter Jeremy --4bRzO86E/ozDv8r1 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAktBHbcACgkQ/opHv/APuIdVdwCfeImKqLrCuqMAirMaIfv1XlIS SMgAn1AvKHm65Q42u/UCAj6Knhh9Ehs+ =OYnh -----END PGP SIGNATURE----- --4bRzO86E/ozDv8r1--