Hello J. R. Okajima,
thank you ver ymuch for your very helpful information.
I don't have /dev/shm in "init" (when AUFS is set up) so I simply
mounted a tmpfs just for AUFS's "xino" file and it works like a charm!
Great!
After a `find / -mount` my debugfs files show these contents:
xib: 16x4096 8192
xigen: 280x4096 160684
Does this mean that AUFS in my case can consume up to approx. 170kb of
RAM (plus the tmpfs layer) ? I could live very well with that...
Thanks again,
Udo
Am 02.11.2015 um 15:25 schrieb sf...@users.sourceforge.net:
> Hello Udo,
>
> Udo Giacomozzi:
>> Problem: When the tmpfs fills up (eg. `cat /dev/zero > /DUMMY`), then
>> the system consistently becomes pratically unusable, meaning that simple
>> commands like `find` or `reboot` can't be run anymore ("command not found").
>>
>> I've also noticed some kernel errors (at least when running for some
>> hours in such a state), but they don't come up immediately:
>>
>> |Oct 31 15:31:01 intermodul kernel: [87752.031289] aufs
>> au_xino_do_write:433:ioget[14146]: I/O Error, write failed (-28) Oct 31
>> 15:31:01 intermodul kernel: [87752.031301] aufs
>> au_xino_write:469:ioget[14146]: I/O Error, write failed (-5) Oct 31
>> 15:31:01 intermodul kernel: [87752.050390] aufs
>> au_xino_do_write:433:ioget[14148]: I/O Error, write failed (-28) Oct 31
>> 15:31:01 intermodul kernel: [87752.050402] aufs
>> au_xino_write:469:ioget[14148]: I/O Error, write failed (-5) # df
> :::
>
> This situation is something similar to creating a new file where the
> filesystem is full. I know you are not creating a file, but for aufs,
> accessing a new file means assigning a new inode number, hence expanding
> the XINO file. The number '-28' means ENOSPC (No space left on device),
> and aufs can do nothing but returning '-5' EIO (Input/output error).
>
> You might not know about XINO files, then I'd suggest you to read aufs
> manual especially "External Inode Number Bitmap, Translation Table and
> Generation Table (xino)" section.
>
> I guess the most appropriate solution for you will be...
> - specify xino=/dev/shm/aufs.xino when mounting aufs
> - your df shows /dev/shm has 256MB free, I guess it will be enough
>
> The long story (if you are interested)
> - you can confirm the current XINO file path via
> <sysfs>/fs/aufs/si_<id>/xi_path.
> - also, for the current size of XINO files, see
> <debugfs>/aufs/si_<id>/{xib,xino[0-9]*,xigen}
> - I guess the path is /root-rw/.aufs.xino, and the consumed blocks is
> very large (most of your /root-rw (65MB))
>
> In order to suppres the growing size of XINO files, aufs provides a few
> mount options such as
> - trunc_xib
> - trunc_xino_path=BRANCH | itrunc_xino=INDEX
> - trunc_xino
>
> But they are not so effective in some cases. the better solution to
> suppres XINO files is to apply tmpfs-idr.patch and vfs-ino.patch against
> your kernel. but I am afraid you don't want to do that. So specifying
> xino= is a good and effective solution for you I hope.
>
>
> J. R. Okajima
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