Re: /usr/share

[Brian May <bam@snoopy.apana.org.au>]

In article <[🔎] 873e34rv02.fsf@erwin.complete.org> you write:
>Hi,
>
>As I recall, the whole idea behind /usr/share, and indeed /usr itself, 
>is that it can be NFS-mounted in a read-only fashion by other
>computers on a network.  This is certainly a great idea, but I have to 
>ask: why does Debian not support this?

I think the biggest problem is keeping the seperate directory structures
in sync with each other. eg is /usr is mounted from a server that
has been recompiled to use glibc 2.1, but /lib still has glibc 2.0,
everything will break!!!! (at least thats the impression I get - I have
not installed glibc 2.1 myself).

>dpkg is not very smart when it comes to these things.  If you install
>package A on the server, you probably have to install package A on the 
>each client as well (unless it is *entirely* contained in /usr or
>/usr/share, as the case may be).  Well, this is not good, because dpkg 
>will barf when refused permission to touch /usr.
>
>How can we deal with this?  Also, what about the issue of keeping
>packages in sync between server and client?

I am working on an unofficial package, diskless, that addresses these
issues, especially the last one. (Although maybe not exactly the way
you want --- it is NOT integrated with dpkg, and some things *might*
not work properly unless you use slink; it does what I want it to
though...). It allows you to setup and maintain (ie automatically
synchronize files on) a NFS server structure that allows you to boot
other computers with a similar setup to that of the server (by default).
The newest version I have made available (see below) on has configurable
options for security, what daemons to run, etc.

I have just finished working on a new "secure" mode which will copy the
contents of /dev and /var to /tmp/dev and /tmp/var respectively on
startup[1]. If you then override the default fstab file to mount /tmp from
the local harddisk, you can get almost the same as what you wanted.
I haven't tested it anywhere except for my own computer, so if you use
it please let me know if it works...

If however, you just want a local copy of /etc, /var, and /dev, and
a global copy of /usr, it should be easy to modify the files to do
this, but it is beyond the scope for me (patches will be considered,
please tell me first though). However, you would need some way to access
both /{var,etc,and dev} on the client and server in order to keep them
synchronised with /usr.

Version 0.1.3 is currently available online at
http://snoopy.apana.org.au/~ftp/linux/

Documentation is installed in the deb file under /usr/doc/diskless.

Please send any comments to me, and do not attempt to file bugs against
my package as I am not yet an official Debian maintainer.

Notes:
[1] somewhat simplified, but you should be able to get the general idea.
/dev and /var are actually symbolic links to /tmp/dev and /tmp/var
respectively. /dev.ro is copied to /tmp/dev and /var.ro is copied to
/tmp/var on startup. Please ask if you want to know more details.