Re: shadowfs

[Tomasz Wegrzanowski <maniek@beer.com>]

On Mon, May 15, 2000 at 07:58:42PM +0530, Pankaj wrote:
> i have a blur idea about shadowfs.
> is there a page that deals with the 
> topic from begining. pls direct me 
> to it so that i can understand what
> is going on.

I doubt there is any manpage,
But I can tell you what shadowfs is to be.

You have 1 directory tree, on 1 filesystem (example: on 1 disk)
and 2nd directory tree, maybe on the other disk.
Shadowfs merges both trees, so :
if you have :
~/1	 - first directory/filesystem
~/2	 - second directory/filesystem
~/shadow - shadowfs merging them both

$ cd ~/1
$ ls
a
b
c
$ cd ~/2
$ ls
d
e
f
$ cd ~/shadow
$ ls
a
b
c
d
e
f

Of course there might be more than 2 directory trees/filesystems/disks

Possible problems are :
- what to do if the same file appear more than one subfilesystem
- what to do if one of subfilesystem changes
- how to implement write side of shadowfs,
- subdirectories of subfilesystems
- if two users have permisions to different set of directories under
  the same name, they might end with seeing other file under the same name

and especially:
- what to do if something actually used is deleted on one of subfilesystems