Date: Wed, 27 Jun 2001 23:31:17 -0700 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Mike Meyer" <mwm@mired.org>, "Andrew Reid" <andrew.reid@plug.cx> Cc: <questions@FreeBSD.ORG> Subject: RE: FreeBSD and surviving unclean shutdowns Message-ID: <001001c0ff9b$efbe1700$1401a8c0@tedm.placo.com> In-Reply-To: <15161.65054.85036.680962@guru.mired.org>
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>-----Original Message----- >From: owner-freebsd-questions@FreeBSD.ORG >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Mike Meyer >Sent: Wednesday, June 27, 2001 8:39 AM >To: Andrew Reid >Cc: questions@FreeBSD.ORG >Subject: RE: FreeBSD and surviving unclean shutdowns > > >Andrew Reid <andrew.reid@plug.cx> types: >> On 26 Jun 2001 03:04:40 -0700, Ted Mittelstaedt wrote: >> > The only problem with all this is that once the system shuts down it >> > won't automatically power back up. (if it's a soft power up system) >> Only one of our servers has this function. It's an Intel Server board >> and it seems to be one of the few Motherboards that I've been able to >> source that features the 'auto-on' when there's power. Some of the >> workstations around here turn on automatically, but I think that's from >> being dropped or something :-) > >This isn't really a problem - if your system shuts down because the >UPS ran out of power, you don't want it to power back up until you're >sure power is restored. Power flickers are common after an outage, so >having the system automatically power up after an outage could lead to >the power to cutting out while you're in the middle of fsck'ing your >file systems. This is very bad juju, and something you don't want to >happen. > Yes, this is a problem. Some of the UPS's handle this by being able to be set to signal power down much earlier than needed, while there's still plenty of reserve left in the battery. The idea being that if you signal power down to the CPU that within a few minutes it will power off, thus the load on the UPS goes away, saving the remaining power in the battery. When AC comes back on and the system restarts, if there is a flicker the UPS will cover for it. It should probably go without saying that if you are running a server or something that really needs to be up 24x7 that you should have it on a generator/ups combo. >Trusting the facility generator got me into that one once, which is >the only time in the last decade I've had a file system fried beyond >the point of restoration. > one trick I do on our news server which has spools that take about 15 minutes per spool to fsck, is I don't set them to be automounted. The system itself is on a 4GB disk but every directory that has any significant activity on it (ie: tmp) as well as all data are on the spools. If the system is abruptly interrupted, the fsck of the nearly empty 4GB disk on reboot is almost instantaneous, also since nothing is normally open or being written to on that disk it's really hard to screw it up. I then remotely access the server and manually fsck and remount the data spools. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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