Date: Wed, 21 Jan 1998 12:30:54 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Calin Andrian <calin@ibd.dbio.ro> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: APC BackUPS driver Message-ID: <XFMail.980121123054.shimon@simon-shapiro.org> In-Reply-To: <Pine.BSF.3.96.980121085317.5071A-100000@ibd.dbio.ro>
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On 21-Jan-98 Calin Andrian wrote: > > > On Tue, 20 Jan 1998, Bruce M. Walter wrote: > >> >> I have a DPT SCSI RAID controller here whose driver uses >> at_shutdown/POSTSYNC to flush it's (enormous!) internal disk buffers. >> When the power goes off during this it insures lost data. I didn't get >> bit by this with your code (I did it all by myself ;) but just wanted to >> warn you in case you wanted to put a note in your tarball. >> >> I have a solution which works in all cases and supports any cable >> configuration, but requires a kernel patch :( I've been looking for a >> way >> around this and will let you know if I find one. Keep up the good work. > > I didn't think there could be any real trouble. I looked through the > standard kernel sources and didn't find any critical devices wanting to > do > anything at shutdown. On the other hand, I gave it a moment's thought > about patching kern_shutdown.c but quit really quick. Now that you opened > my eyes I think that maybe it's time to add another option (and list of > routines - or only ONE routine) to at_shutdown. Something like > at_shutdown(func, arg, SHUTDOWN_FOR_REAL) ment specifically for shutting > down power. I think you need to be a bit more careful than that. You should not force a shutdown before ALL drivers have completed their at_shutdown calls. This is essential. The purpose of a UPS is to extend the system's life, to avoid power failure disasters. While you are looking around that code, try to hunt down this problem: Sometimes, after at_shutdown is called, the rebooting code actually tries to flush buffers. At this point, the DPT has already shutdown. > > I'll look into it. > > I'd like to work on it now that I already started this UPS matter. > > Later, > > Calin > > ---------- Sincerely Yours, Simon Shapiro Shimon@Simon-Shapiro.ORG Voice: 503.799.2313
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