Re: Multiple instances of the same mount point in fstab not possible? (want to layer multiple filesystems into one namespace via union mount option)

[mlelstv%serpens.de@localhost (Michael van Elst)]

mp%petermann-it.de@localhost (Matthias Petermann) writes:

>NAME=data1             /export   ffs     rw,log,union          0 0
>NAME=data2             /export   ffs     rw,log,union          0 0
>NAME=data3             /export   ffs     rw,log,union          0 0

>Here, only the first file system is mounted, the other two are ignored. 
>I suspect that multiple occurrences of the same mount point are not 
>supported in fstab.

It's a feature. mount -a skips filesystems that are already mounted,
so you don't get failures from the attempt to mount a filesystem twice.
(mount -A forces all mounts).

But your example has another issue, there is no information about the
order of mounts, so you may end with filesystems stacked incompletely
or even the wrong order.

The easiest is probably to declare the filesystem 'noauto' and add
a custom rc script that creates and removes your stacked filesystems.