Installing Linux (without CD/floppies)

[Ashley Pittman]

On Tue, 2003-02-18 at 15:18, Robert G. Brown wrote:
> > I've often wondered that, at the very least if you are going to install
> > then you should just download a tgz of the root partition rather than
> > the hassle of automagically installing/configuring packages.
> 
> With kickstart it is actually easier to do the latter.  A single
> kickstart script can install all the nodes, typically, and have a
> boilerplate DHCP entry.  It reduces an install (once set up) to:
> 
>   a) boot via pxe to a set of bootable kernel images with timeout to the
> primary hard disk image (e.g. grub), if there is one.
>   b) select the network/kickstart install kernel, set up to
> automatically default straight into dhcp/kickstart.
>   c) in four to five minutes the system reboots itself (in the %post
> step) into operational mode, ready to run.

This is the system we use here, it works really well, to re-install you
just create a symlink in the dhcp config directory (based on a hex
representation of the IP address) and then re-boot the node.  Everything
else is automatic.

Takes a tiny ammount of admin time but you do have to wait for the node
to finish.  One problem we have here is that it installs a entire cd's
worth of software, most of which never gets used, a quick look shows
that there is 650Mb of software installed on our compute nodes, thats
*far* to much.

> Package based installs are also trivial to update or to add new packages
> to, and timely updates are ESSENTIAL to cluster (or LAN) management.
> See for example, the "yum" tool, which pretty much totally automates
> package management including the installation of new packages and their
> fully automatic updating from a designated install server.  Anything
> from a new kernel to a new package to a security update in an existing
> package automagically propagates to the nodes once placed in the install
> server tree.  With a tgz-based installation, you might as well just
> rebuild the tgz image and do a full reinstall.  This is enough work that
> (of course) it will get put off, which can be disasterous with security
> updates.

Agreed, I wasn't thinking of maintaing your own packageless distro, more
of having a complete filesystem tree that you could chroot into for
admin and maintanince, keeping a tar.gz copy of this tree for efficiancy
and "installing" a node by untaring this file onto the local disk.

My reasoning was to get the node install time as *low* as possible and I
was assuming that kick-start wasted to many cycles/bandwidth on stuff
that would just end up the same anyway. kick-start wouldn't allow you to
customise the image as much either.

This would take some effort to setup the "install" script and possibly
wouldn't be worth it because it would only save a few minutes (in
parallel) of unattended time while the node installs itself.

However... Once you have got the node-install time low enough then you
have the possibility of requesting node configurations when you submit
your jobs, they could install with a different flavour of the os and
different kernels depending on what requirments the job has.  I've not
heard of anybody doing this though so perhaps it isn't desirable but I
know I can think of uses for it.

Ashley,