Date: Thu, 25 Sep 2008 22:33:13 +0200 From: =?ISO-8859-1?Q?Nejc_S=28koberne?= <nejc@skoberne.net> To: David Polak <me@davidpolak.com> Cc: freebsd-questions@freebsd.org Subject: Re: mount_unionfs for jails Message-ID: <48DBF589.3030906@skoberne.net> In-Reply-To: <005401c91f35$3cf09fa0$b6d1dee0$@com> References: <005401c91f35$3cf09fa0$b6d1dee0$@com>
next in thread | previous in thread | raw e-mail | index | archive | help
Hello, > Here is what I am trying to do: > > mount_unionfs -o below /usr/jails/basejail /usr/jail/jail1 > > after I do that I edit /usr/jail/jail1/etc/rc.conf and add the appropriate > entries to the host system rc.conf, but when I start the jail it starts > using the settings from /usr/jails/basejail. I have the same setup and it works for me. > Is my mount_unionfs syntax wrong, is this a bug in unionfs (man page says > unionfs is broken, but doesn't specify how its broken) or is this expected > behavior? It shouldn't be wrong. I have this in my fstab: /jail/base /jail/spl/nejcspl unionfs rw,noatime,below 0 0 (noatime option is completely optional, of course.) But, if I were you, I would update the RELEASE to STABLE. This will also fix some bugs in unionfs. However at least some other bugs still aren't fixed in 7-STABLE to this day (most notably the socket bug, which prevents mysql from running in a jail and writing socket file to /tmp/mysql.sock), so we had to MFC the patch from HEAD manually. If you need the patch, let me know. However, I don't suggest running jails on top of unionfs where you need decent stability (i.e. in production). I am writing thesis at the moment which also covers this topic. We also stumbled upon these issues: - socket file bug, mentioned before, still present in 7-STABLE, no ideas when it will be MFCed; - "mv" bug (see freebsd-fs archives for August 2008, me and my friend posted a few posts there) which causes troubles when moving directories (files would appear as gone and then reappear again) which exist or don't exist on lower and upper levels; - another "mv" bug which I discovered yesterday and seems to be very strange and hard to replay - I didn't even mess with the lower level, it seems that also just the upper layer can behave strangely sometimes (erros like "mv: invalid argument" when simply trying to move a big (>10 GB) directory - the error was gone after I restarted the jail (i.e. also remounting the unionfs); - strange behaviour of some applications (apache in my case) not "seeing" the lower layer (/etc/hosts most notably) - we had to do "touch" (and then copy to all jails on change) on files we _really_ need to be visible. However, after we "fscked" our partition with unionfs directories, we weren't able to reproduce this error; - UFS filesystem would get to inconsistent state (we don't know exactly when) so some commands would behave strangely and fsck (see above) is needed in single user mode; - _most notably_: there hasn't been a single reply to our unionfs related problem reports and posts to freebsd-fs list. So I guess that people who are in charge for unionfs in FreeBSD aren't really responsive and that the future of unionfs in FreeBSD isn't really bright. It's a pity, though, since this is a very useful feature, especially for jailed systems. However, hope remains, that things will be fixed at least in 8.0 if not in 7.1. So, you can see that there are (still) many issues with unionfs on FreeBSD. Please let me know if you are able to solve your problem. Or else we can make this list a little longer. :) HTH, Nejc
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?48DBF589.3030906>