Distributing directory over multiple discs ?

[Pieter de Goeje]

On Saturday 15 December 2007, Tino Engel wrote:
> Frank Staals schrieb:
> > Since one of my discs is filling up rather quickly (Say disc A ) while
> > an other one stays quite empty (say disc B ) I would like to
> > distribute the content of a directory on disc A over both A and B. I
> > know I can simply move some of the files over to a sperate directory
> > on disc B but is is possible to somehow merge the 2 ? So for example
> > if I would do an ls in discA/dir I would also see the files that are
> > stored on discB/an/other/dir ? And off-course if this is possible how
> > can I acchieve something like that
> >
> > Regards,
>
> I think on debian it used to be (or it is, dunno, I use freebsd now)
> possible to mount 2 filesystems on one mount point. the OS then took
> care of assigning the space. Well, I do not want to try it on my system
> though...

On FreeBSD this is called "unionfs". Take a look at mount_unionfs(8) and 
mount(8)'s "union" option.

HTH,
Pieter de Goeje