fedora-l] Migrating from RH9 Legacy to CentOS 3

[Paul Lee]

R P Herrold wrote:
> On Tue, 24 Oct 2006, David Eisner wrote:
> 
>> With the end of Legacy support for RH9, I'd like to migrate my Fedora
>> Legacified RH9 box to Centos 3.
>>  http://www.owlriver.com/tips/centos-31-ex-rhl-9/
>> Any thoughts on whether this should also work with the .legacy packages?
> 
> 
> As author of the migration instructions in question, let me give an 
> unqualified "Yes, probably" ....  ;)
> 
> I would feel safer 'stretching' into CentOS-4, just to get the later 
> kernel, and buying the longer lifespan, but a move with a set of CentOS 
> 3.8 spins ISO images will work, if you are a dead plain install wholly 
> mediated by RPM, with minimal or no transition issues.  But please:
>     1.      level 0 backup
>     2.    strip out unused packages -- a good idea
>         anyway
>     3.    possibly reboot and force a full fsck on all
>         partitions
>     4.    remove /home if at a separate mountpoint, from
>         the fstab -- no reason to risk the data
> 

I may be introducing another layer of complication here but I have found 
various OS Virtualization tools such OpenVZ extremely handy for for 
migrating / updating servers with legacy RH operating systems.

Basically we have had a spare server where we have loaded the latest 
Centos OS and installed the openvz kernel and utilities (all in RPM 
format) and reboot.

All we have to do then is copy/backup the legacy RH9 server into a the 
new openvz node (typically into /vz/private/<veid)). Basically rsync / 
/home /var /usr etc (you don't need /boot or /lib/modules as you won't 
be running the RH9 kernel) . Then create a ve conf file for the RH9 VPS
and then boot the RH9 VPS (easier if your VPS hardware node is on the 
same IP subnet).

With your virtualised RH9 "server" running in VPS you are free to 
reformat or re-install the original server. If when you have 
re-installed the server and copied over the data, you find something is 
broken, just fall back to your VPS "copy."

You could even test an OS upgrade using yum from within a VE before you
carrying out an upgrade on a real server.

On this particular server we are running 5 OS's including RH9 under an 
openvz test kernel (there is now a new version of this kernel ;o)) :

[root at vm5 config]# cat /etc/redhat-release
CentOS release 4.3 (Final)

[root at vm5 ~]# uname -a
Linux vm5.xxxxxx.com 2.6.16-026test014.4-smp #1 SMP Wed Jun 7 17:01:29 
MSD 2006 i686 i686 i386 GNU/Linux

[root at vm5 ~]# vzlist
      VPSID      NPROC STATUS  IP_ADDR         HOSTNAME
       6001         35 running 83.xxxxxxxxxx   secure1.xxxxx   <--RH9
       6002         58 running 83.xxxxxxxxxx   server1.xxxxx   <--Centos3
       6003          1 running 83.xxxxxxxxxx   test-gentoo.xxxx<--Gentoo
       6004         49 running 83.xxxxxxxxxx   server1.xxxx    <--RH9
       6006         26 running 83.xxxxxxxxxx   status.xxxx     <--FC6

Also has the advantage that we were able to run 10 or more (legacy) VPS 
on the same physical hardware freeing up lots of real boxes (depends on 
how busy the servers are and the power of the hardware node).

The only thing is I have not been able to create pristine RH9 template 
using yum (but then again I don't need to as I just copy legacy boxes). 
When FC6 came out this week it was a doddle to create an FC6 template 
and boot an FC6 VPS.

There are other virtualisation technologies such as xen and vserver and 
openvps etc which would help ease migration paths - all you need have is 
one spare server, but I have jut found openvz the easiest to configure 
and setup.

www.openvz.org

Regards


Paul Lee
Weycrest.Net