Hi Michael,
I don't know what is going on in detail here. Since the kernel log says
something about AFS cache scan before the crash, there might be some
issue with your cache partition. If your overlay covers the entire
client filesystem, does that include AFS cache as well? Would it be
possible to either mount a non-overlay partition for the cache (disk or
ram)? Another workaround might be to use a memory cache instead of a
disk cache.
Best,
Volkmar
Am Donnerstag, den 06.10.2016, 09:20 +0000 schrieb Richter, Michael:
> Hi,
>
> I’m using Ubuntu 12.04 on ~240 computers for years with this
> configuration without problems. I’m now trying to migrate to Ubuntu
> 16.04. Ubuntu is booted with readonly filesystem. A initramfs script
> sets an union fs on top to bring write access. Nearly the same as on
> every live CD.
>
> On top there is the OpenAFS client. Which connects the users home
> share on log on. But the OpenAFS client crashes on system boot.
>
> If I disable OpenAFS completely and use accounts from another domain
> without OpenAFS share, everything works. If I don’t use the overlay
> and mount the drive read/write OpenAFS is working too. Only the
> combination of OpenAFS and OverlayFS (or AuFS) is not working.
>
> I also tried Ubuntu‘s Upstream Kernel and the OpenAFS client from
> OpenAFS website. Nothing helped.
>
> This is what I do in initramfs‘ init-bottom script:
>
> ~~~
> ro_mount_point="${rootmnt%/}.ro"
> rw_mount_point="${rootmnt%/}.rw"
>
> echo Create mount points for the read-only and read/write layers:
> mkdir "${ro_mount_point}" "${rw_mount_point}"
>
> echo Move the already-mounted root filesystem to the ro mount point:
> mount --move "${rootmnt}" "${ro_mount_point}"
>
> echo Mount the read/write filesystem:
> modprobe -r zram
> modprobe zram num_devices=4
> echo 1 > /sys/block/zram0/reset
> echo lz4 > /sys/block/zram0/comp_algorithm
> echo 2 > /sys/block/zram0/max_comp_streams
> echo 3G > /sys/block/zram0/disksize
> mke2fs /dev/zram0
> mount -t ext2 /dev/zram0 "${rw_mount_point}"
> # also tried tmpfs here
> #mount -t tmpfs -o rw,noatime,mode=755 root.rw "${rw_mount_point}"
> mkdir "${rw_mount_point}/upper"
> mkdir "${rw_mount_point}/work"
>
> echo Mount the union:
> mount -t overlay -o
> "lowerdir=${ro_mount_point},upperdir=${rw_mount_point}/upper,workdir=
> ${rw_mount_point}/work" overlay "${rootmnt}"
>
> mkdir "${rootmnt}/ro" "${rootmnt}/rw"
> mount --bind "${ro_mount_point}" "${rootmnt}/ro"
> mount --bind "${rw_mount_point}" "${rootmnt}/rw"
> ~~~
>
> I also attached the crash part from kern.log.
>
> Do someone know how to get this working? Is it a bug? Am I doing
> something wrong?
>
> Michael Richter
>
> --
> Michael Richter
>
> Technische Universität Berlin
> Universitätsbibliothek
> IT-Service
>
> Fasanenstraße 88, 10623 Berlin
> Telefon: +49 (0)30 314-76310
> m.rich...@tu-berlin.de
>
> www.ub.tu-berlin.de
>
