[linux-lvm] read-only media in a LVM?

[Wolfgang Weisselberg]

Sean P. Kane wrote 78 lines:

> I'd love to have a unionfs, but my understanding is that no such beast
> exists for Linux 2.4 currently

Try looking at 
    http://plasticfs.sourceforge.net/plasticfs.html

Plasticfs-viewpath is basically a unionof all filesystems in
the viewpath, changes happen on the first one and a .whiteout
remembers what you deleted.  It does *not* work for root
(security!!!  You do not want root to see /tmp/login instead of
/bin/login!).  Remember to set the environment variables, e.g.

    LD_PRELOAD=/usr/local/lib/libplasticfs.so
    PLASTICFS="viewpath /ramdisk /cdrom1 /cdrom2"
    /bin/bash   # or whatever program you want.

Since Plasticfs works on file-level, you should be able to mix
and match filesystems as you like.  Note however that --- since
we just overload common FS access methods --- some things might
not work.

I have it in production use (for Aegis, not for cdroms).

-Wolfgang