[ale] read only filesystems (was: RE: [ale] firewalls on cd)

[hirsch at zapmedia.com]

John Wells writes:

 > Also, if you can run a complete distribution off of a
 > cd, is it possible to make your own hd's filesystem
 > read only?  I know the root filesystem is intially
 > read only at boot...is it possible to cause it to
 > remain that way and still function?

Yes.  I've done this.  There are some files that must be
writable--mostly notably stuff in /var/ like log files and utmp.  You
need to create a ramdisk for these files.  I then created symlinks
from var to the ramdisk.

Another problem, with some distributions, when you log in many devices
change ownership.  My solution was to use devfs, so the devices don't
really exist on the file system in the first place.

After implementing these ideas I was able to boot RedHat on a
read-only filesystem.  It was kind of neat being able to just power
off without any fsck penalty.  (This was before the release of
reiserfs/xfs/jfs/ext3.)

--Michael



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