[Dazuko-devel] Re: Kernel panics with dazukofs

[jim burns]

Ok, here's a summary of my experience with dazukofs on SuSE 10.2, reiserfs.

1) Automatically eliminated as candidates for being overlaid are /dev, /proc, 
& /sys. I get major samba problems if I try (100% cpu usage), and my virus 
checker (antivir) doesn't even include /sys & /proc in scans, anyway.

2) The most common problem is 'umount' segfault-ing if I try to overlay 
certain directories. (This would cause shutdowns to hang 
after /etc/init.d/boot.localfs. Directories that segfault umount are also 
most likely to be the ones that panic KDE, starting with kswapd0.) The first 
problem was with /lib. I then tried to overlay only the subdirectories 
of /lib, and ended up with /lib/security as the only one that segfault-ed 
(not /lib/modules, as I originally feared). I then tried moving /lib/security 
(contains pam libraries that kdm and login leep open) to another directory 
that wasn't overlaid, and sym-linking to it, but /lib still segfault-ed 
umount. Obviously, this is undesirable to only overlay subdirectories 
of /lib, and not the libraries in /lib.

I had similar problems with /usr, and had to check which subdirectories were 
segfault-ing umount: /usr/lib & /usr/X11R6 (which really only has fonts, and 
my nvidia libraries, since I have Xorg 7).

Not being able to overlay the libraries in both /lib and /usr/lib means 90% of 
my program libraries are unprotected.

3) I also couldn't overlay /var, with umount complaining 
that /var/lib/nfs/rpc_pipefs was busy. No segfault, no hang in shutdown, but 
I just erred on the side of caution, and only overlay-ed the other 
directories of /var.

I didn't try seeing which subdirs of /var/lib could be overlay-ed, as I 
already have 40 overlays in my fstab, and dazukofs seems to have a hard disk 
space overhead - I'm missing around 30Mb. Since there are some 47 
subdirectories of /var/lib, I left well enough alone.

4) I couldn't overlay /sbin or /usr/sbin - I get some services reporting 
failure on startup, even though the processes themselves are visible in ps. 
This causes problems with .pid files not being written, and errors reported 
on service stops. Even after eliminating those two dirs, 'dbus' was reporting 
failure on startup, and I had to not overlay /usr/bin.

Since antivir doesn't start until after most of these services are started, I 
doubt antivir is slowing things down.

At least I can still overlay /bin & /lib/modules.

5) Finally, I don't overlay mount points. I don't mind not overlay-ing remote 
mount points - servers should be responsible for their own virus checking. 
However, I can't even overlay local mount points - they just disappear. This 
includes a win98 vfat mount, and an xp ntfs mount using the fuse based 
ntfs-3g r/w driver. I can't even overlay the parent directory of these mount 
points - the local mounts just disappear.

Any ideas? Thanx.