Date: Mon, 4 Jan 2010 09:44:07 +1100 From: Peter Jeremy <peterjeremy@acm.org> To: Aristedes Maniatis <ari@ish.com.au> Cc: freebsd-current@freebsd.org Subject: Re: [PATCH] Shutdown cooloff feature Message-ID: <20100103224407.GB76049@server.vk2pj.dyndns.org> In-Reply-To: <4B405C3D.7090501@ish.com.au> References: <4AC141B0.4090705@delphij.net> <alpine.BSF.2.00.0909291245080.91454@fledge.watson.org> <hhoobp$grh$1@ger.gmane.org> <4B405C3D.7090501@ish.com.au>
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--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 <ari@ish.com.au> 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--
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