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

[Sean P. Kane]

Thanks for all the useful thoughts and pointers. I'll give them a try
and see what I can manage to pull together.

Sean

------------------------------------------------------------------------
Sean P. Kane
spkane at genomatica.com
Lead Infrastructure Architect
Genomatica, Inc.
------------------------------------------------------------------------
"When we destroy something man has created we call it vandalism......
 When we destroy something that Gaia has created we call it progress."


-----Original Message-----
From: Wolfgang Weisselberg [mailto:uzx87lvfmukwc001 at sneakemail.com] 
Sent: Monday, June 23, 2003 17:35
To: linux-lvm at sistina.com
Subject: Re: [linux-lvm] read-only media in a LVM?


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

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