Date: Sun, 24 Oct 2004 10:43:04 -0500 From: Vulpes Velox <v.velox@vvelox.net> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-fs@freebsd.org Subject: Re: Unionfs and nullfs question Message-ID: <20041024104304.1620e1ab@vixen42.24-119-122-191.cpe.cableone.net> In-Reply-To: <20041023113958.X16873@ganymede.hub.org> References: <20041022174052.4a203268@fennec> <20041023113958.X16873@ganymede.hub.org>
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On Sat, 23 Oct 2004 11:47:57 -0300 (ADT) "Marc G. Fournier" <scrappy@hub.org> wrote: > On Fri, 22 Oct 2004, Vulpes Velox wrote: > > > I am guessing the answer, given the big warning in the man for > > both is that this is going to be a no that both are dangerous to > > the data and luck is mainly involved in not having the data > > screwed over, but just wanna check :) > > I run over 200 VPSs over 4 machines with all application data > (installed ports) mounted through unionfs to reduce disk space usage > ... every once in a blue moon, I'll get a crash resulting from a bug > in the unionfs code, but it isn't as bad as it was, say, a year ago > ... but I am running production servers with it. > > There are a few things you can't do right now ... for instance, I > don't have /var union mounted, as FIFO's/sockets tend to > consistently blow it up ... but, my more loaded server looks like: > > # df -t union | wc -l > 73 > # uptime > 11:41AM up 47 days, 22:25, 1 user, load averages: 12.12, 20.67, > 22.46 > > There is an annoying 'bug' in fsck that Don Lewis has been working > on correcting that is very exasperated by unionfs ... namely how the > list of inodes to check is generated. If you, for instance, mount a > blank file systems over top of /usr/ports, and then do a find of > /usr/ports, the blank file system will fill up with a bunch of > directories to 'mirror' ports ... the files don't come through, only > the directories. On a crash, the OS leaves behind a bunch of ZERO > LENGTH DIRECTORIES ... I've had fsck run for 12-14hrs after one of > these, its that messy :( Don has been working on a patch to handle > the ZLDs better, but it hasn't been committed to -stable yet, > pending more testing ... I'm running it live here, but *knock on > wood* haven't had a crash since putting it into place ... Cool, thanks for the info. I eventually decided to go with doing a mount_nfs -o union for it :) >From one of the conversations I found previously, this is suppose to be safer than doing doing a regular mount_unionfs.
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