[CentOS] Update/upgrade paths?

[Sean O'Connell]

On Sun, 2005-09-18 at 13:13 -0700, Dave Laird wrote:
> Good afternoon, Netizens...
> 
> I have a number of 3.3 CentOS boxes that are quite a substantial distance
> from my home office. Short of physically going to those sites with a fresh
> set of CD's in hand, is there a method of remotely (via secure SSH)
> updating not only the files but the distribution as well, say to 4.1? Can
> you do a distribution update without using CD's? 
> 
> After a few weeks of experimenting with CentOS 4.1 I am really motivated
> to upgrade, if for no other reason than the fresh kernel and x.org, to
> name just a few. 

If you are willing to do kickstarts, then, yes. you can do this. Add a
reinstall entry to your /etc/grub.conf using vnc (you connect to
myserver:1)

title Reinstall System
        kernel /vmlinuz-reinstall ks=<URL>/server-reinstall.cfg vnc
        initrd /initrd-reinstall.img

where vmlinuz-reinstall and intrd-reinstall.img are the vmlinuz and
initrd.img from the pxe subdirectory of os/<arch>/images/pxeboot that
you need to download and drop in /boot (the above assumes /boot is its
own partition otherwise you'll need /boot/vm..). There are a bunch of
issues with doing this:

1) are you comfortable with kickstart?
2) are the machines using static addressing or dhcp? if static, then
you'll have to add a few command line parameters:

ip=w.x.y.z netmask=255.255.255.0 gateway=w.x.y.1 dns=w.x.y.2

3) you'll probably want to add a vncpassword=xxxxx flag as well

You'll probably want to play with a local machine first (and make sure
someone is there to push a power button :).

Hope that helps,
Sean