BURKS 2/BURKS_AUG97.ISO/BURKS/LINUX/HOWTO/mini/nfsrootc.txt

Text File | 1997-07-07 | 16KB | 350 lines

  NFS-Root-Client Mini-Howto
  Ofer Maor, [e-mail]
  v3, 5 December 1996

  The purpose of this Mini-Howto is to explain how to create client root
  directories on a server that is using NFS Root mounted clients.
  You can find the latest version of this Howto (HTML or Text) at
  URL: http://www.hadar.co.il/ofer/nfs-root-client/

  1. Copyright

  (c) 1996 Ofer Maor <[e-mail]>

  Unless otherwise stated, Linux HOWTO documents are copyrighted by
  their respective authors. Linux HOWTO documents may be reproduced and
  distributed in whole or in part, in any medium physical or electronic,
  as long as this copyright notice is retained on all copies. Commercial
  redistribution is allowed and encouraged; however, the author would
  like to be notified of any such distributions.

  All translations, derivative works, or aggregate works incorporating
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  may be granted under certain conditions; please contact the Linux
  HOWTO coordinator at the address given below.

  In short, we wish to promote dissemination of this information through
  as many channels as possible. However, we do wish to retain copyright
  on the HOWTO documents, and would like to be notified of any plans to
  redistribute the HOWTOs.

  If you have questions, please contact Ofer Maor <[e-mail]>, the
  author of this mini-HOWTO, or Greg Hankins, the Linux HOWTO coordinator,
  at [e-mail] via email.

  If you have anything to add to this Mini-Howto, Please mail the author
  (Ofer Maor <[e-mail]>), with the information. Any new relevant
  information would be appreciated.

  1.1. Thanks

  I would like to express my thanks to the author of the NFS-Root Howto,
  Andreas Kostyrca ([e-mail]). His Mini-Howto helped me
  with the first steps in creating a NFS Root Mounted client. My
  Mini-Howto does not, in any way, try to replace his work, but to
  enhance it using my experiences in this process.

  I would also like to thank Mark Kushinsky ([e-mail]) for
  polishing the english and spelling of this Howto, thus making it much
  more readable.


  2. Preface

  This Mini-Howto was written in order to help people who want to use
  NFS Root mounting to create their client's directories. Please note
  that there are many ways to accomplish this, depending on your needs
  and intent. If the clients are individual, and each client has its own
  users and administrator, it will be necessary to make significant
  parts of the client dirs not shared with other clients. On the other
  hand if the client is intended for multiple users, and are all
  administrated by the same person (for instance, a computer class),
  make as many files as possible shareable in order to make
  administration more manageable. This Howto will focus on the second
  issue.

  2.1. General Overview

  When building a client's root directory, and trying to limit ourselves
  to the minimum client size, we mainly focus on which files can we
  share, or mount from the server. In this Howto I will recommend the
  configuration of a client based on my experience. But before we begin
  please note:

  * This Mini-Howto does not explain how to do the actual NFS Root
    mounting. Reffer to the NFS-Root Mini-Howto if you need more
    information about that issue.

  * I based most of my client's configuration on  mounts and symbolic
    links. A lot of those symbolic links can be replaced by hardlinks.
    One should choose according to his personal preference. Putting a
    hardlink over a mount and a symbolic link has its advantages, but
    might cause confusion. A file will not be erased until all its
    hardlinks are removed. Thus, In order to prevent a case in which you
    upgrade a certain file, and the hardlinks still refer to the older
    version, you will have to be very careful and keep track of every
    link you put.

  * While mounting the information from the server, two concepts can be
    used. The first (most common) concept, is to mount the whole server
    root directory under a local directory, and then just change the
    path or link the relevant directories there. I personally dislike
    mounting root partitions of a server on clients. Thus, this Howto
    suggests a way to mount the relevant directories of the server to
    the relevant places on the system.

  * This Howto is based on my experience building client directories on
    a Slackware 3.1 based distribution. Things may be different
    (especially on the rc.* files), for other users, however the
    concepts should still remain the same.


  3. Creating the client's root directory

  3.1. Creating the directory tree

  First of all, you need to create the directory structure itself. I
  created all the clients under /clients/hostname and I will use it for
  my examples listed below. This, however, can be changed to anything
  else. The first stage, then, is to create the relevant directories in
  the root directory. You should create the following directories:

    bin, dev, etc, home, lib, mnt, proc, sbin, server, tmp, usr, var

  and any other directories you might want to have on your system.

  The local, proc, and dev directories will be used separately on each
  machine while the rest of the directories will be either party or
  completely shared with the rest of the clients.

  3.2. Creating the minimal file system needed for boot

  3.2.1. Creating the dev dir.

  Although the dev dir can be shared, it is  better to create a separate
  one for each client. You can create your client's dev directory with
  the appropriate MAKEDEV scripts, however in most cases it is simpler
  just to copy it from the server:

    cp -a /dev /clients/hostname

  You should keep in mind that /dev/mouse, /dev/cdrom and /dev/modem are
  symbolic links to actually devices, and therefore you should be sure
  that they are linked correctly to fit the client's hardware.

  3.2.2. Copying the necessary binaries.

  Although we mount everything from the server, there is a minimum that
  we need to copy to each client. First of all, we need "init", our
  system will not be able to run anything before init'ing (as the author
  found out in the hard way ;-). So first, you should copy /sbin/init to
  your client's sbin dir and then so that rc.S will run, you should copy
  /bin/sh to the client's bin directory. Also, in order to mount
  everything you need to copy /sbin/mount to the client's sbin directory.
  This is the minimum, assuming the first line in your rc.S is mount -av.
  However, I recommend copying a few more files: update, ls, rm, cp and
  umount, so that you will have the basic tools in case the client has
  problems mounting. If you choose to leave your swap on line before
  mount, you should also copy the swapon binary.

  Since most of these binaries are by default dynamically linked, you
  will also need to copy a fair part of /lib:

    cp -a /lib/ld.* /lib/libc.* /lib/libcursses.* /client/hostname/lib

  Hardlinking the binaries themselves, instead of copying them, should
  be considered. Please read my comments on this in part 2.1 of this
  Howto.

  Please notice, all of the information above assumes that the kernel
  has been given the network parameters while booting up. If you plan to
  use rarp or bootp, you will probably need the relevant binaries for
  these as well.

  Generally, you will need the minimum of files that will enable you to
  configure the network and run rc.S up to the point where it mounts the
  rest of the file system.

  3.2.3. The var directory

  The var directory, in most cases, should be separate for each client.
  However, a lot of the data can be shared. Create under the server
  directory a directory called var. We will mount the server's var
  directory there. To create the local var directory, simply type:

    cp -a /var /clients/hostname/

  Now, you have a choice as to what you want to sep