unionfs and nullfs combination

[Kurt Jaeger]

Hi!

> One relatively cheap way to create thin jails in the pre-ZFS era,
> was to combine nullfs and unionfs (1). This seem to work only in
> 10 and previous branches. Do you use such a combination?

We had this running with FreeBSD 6.x, but unionfs had issues,
among them the whiteout problem.

If you have a directory where many small files with random
names are created in the upper layer, and deleted afterwards,
the directory in the upper layer grows with each file because
of the way whiteout files are handled. There's a mount option
whiteout=whenneeded that should fix this, I no longer remember
what stopped us from using it.

> It seems like a very relevant feature nowadays, when people
> use all these cloud-based systems, which oftentimes have little
> resources to run ZFS and UFS is most likely a better choice...

Funny, I have the impression that disk space, RAM and CPU are
plenty compared to the past, so I would prefer ZFS anytime now.
Our next jail box will probably use ZFS dedup with lots of RAM.

-- 
pi at opsec.eu            +49 171 3101372                         3 years to go !