Date: Sun, 16 May 2004 11:30:40 -0500 From: Dan Nelson <dnelson@allantgroup.com> To: Michael Hamburg <hamburg@fas.harvard.edu> Cc: freebsd-current@freebsd.org Subject: Re: fsck in -current Message-ID: <20040516163039.GE29158@dan.emsphone.com> In-Reply-To: <FA17DF77-A6FB-11D8-89DA-0003939A19AA@fas.harvard.edu> References: <20040515220258.H920@ganymede.hub.org> <D3AE316C-A6D9-11D8-89DA-0003939A19AA@fas.harvard.edu> <20040515233728.Q30269@ganymede.hub.org> <FA17DF77-A6FB-11D8-89DA-0003939A19AA@fas.harvard.edu>
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In the last episode (May 16), Michael Hamburg said: > On May 15, 2004, at 10:41 PM, Marc G. Fournier wrote: > >On Sat, 15 May 2004, Michael Hamburg wrote: > >>On May 15, 2004, at 9:08 PM, Marc G. Fournier wrote: > >>>I'm seriously considering putting 5.x onto my next server, to take > >>>advantage of, if nothing else, the reduction in the GIANT LOCK > >>>reliance ... one "concern" I have is how fsck works in 5.x ... > >>> > >>>Right now, on 4.x, I have an fsck running that has been going for > >>>~3hrs now: > >>> > >>># date; ps aux | grep fsck > >>>Sat May 15 22:04:00 ADT 2004 > >>>root 40 99.0 4.5 185756 185796 p0 R+ 6:55PM 164:01.60 fsck -y /dev/da0s1h > >>> > >>>and is in Phase 4 ... > >>> > >>>In 5.x, if I'm not mistaken, fsck's are backgrounded on reboot, so > >>>that the system comes up faster ... but: > >>> > >>>a. wouldn't that slow down the fsck itself, since all the > >>>processes on the machine would be using CPU/memory? > >> > >>Yes. You can probably renice it or something, though, and it > >>wouldn't take that much longer. Fsck takes very little CPU; it's almost all disk I/O, and bgfsck tries to throttle its load if it thinks that there's too much disk load. > You don't need much space unless you have high turnover -- the > default extra space in FFS that you can't allocate anyway should be > plenty, but as far as I can tell, if you do run out of space, Very > Bad Things Happen (tm). Just what those Very Bad Things are probably > depends on the release. The only Vary Bad Thing that I've ever seen happen is processes start returning ENOSPC even though df claims there's lots to spare. As soon as the fsck finishes you get your space back. -- Dan Nelson dnelson@allantgroup.com
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