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Re: fedora-l] Migrating from RH9 Legacy to CentOS 3



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

[root 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 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







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