Upgrading CentOS 4.8 (final) to 5.x

Is it possible ? If I try a fresh install, it means I have to disconnect server, backup everything, install new OS, then install virtualmin and restore everything from backup ... (should it work backup restore if it's from centos 4 to centos 5 ?) You understand it will be very long ... I was searching if it was possible to upgrade os version (like in ubuntu) but wasn't able to find an answer.

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Joe's picture
Submitted by Joe on Mon, 10/26/2009 - 06:13 Pro Licensee

This would be a question for the CentOS folks. Their docs cover upgrades in pretty good detail, I think.

There is no equivalent to "apt-get dist-upgrade" on CentOS, if that's what you're asking, though it is possible (for extremely experienced admins who have good backups and a lot of patience) to perform an upgrade using yum. But this is not a supported upgrade method from the CentOS folks (Fedora 10 and 11 have pretty good yum upgrade support, though, so I suspect CentOS 6 will have the ability to upgrade from the command line similarly to a dist-upgrade on Debian/Ubuntu). In the meantime, the upgrade process is to download the CD or DVD ISOs, reboot into the installer, and perform the upgrade. You always need good backups, when doing any sort of major change to your system, and there will be downtime, but it should be pretty painless. I've performed CentOS upgrades in the past and had the system back in service in about an hour.

Anyway, you're asking the wrong folks. We may know more than the average user about CentOS, but we didn't build it, and aren't really the best folks to ask about it.

Ok understood

Just last questions:
If I build a new fresh server with latest OS:

1) Which OS is the best suggested ? (I always used CentOS for server and Ubuntu for my local PC)
2) Will backup of every domain and services done with actually installed CentOS 4.8 work with a restore after new OS installed ?

If I have undesrtood all I have to do is:
1) Backup everything with virtualmin tool
2) Prepare new server with fresh OS
3) Install virtualmin pro with the script you provide
4) Restore from backup saved with virtualmin tool

1) Which OS is the best suggested ? (I always used CentOS for server and Ubuntu for my local PC)

You can see the OS's here that have "Grade A" support:

http://virtualmin.com/os-support

Your current system of using CentOS for servers should work great -- CentOS is well supported, and used by a good majority of the folks using Virtualmin.

2) Will backup of every domain and services done with actually installed CentOS 4.8 work with a restore after new OS installed ?

Yup! The backups are generic, in that the OS or distribution they're performed on should not matter.

If I have undesrtood all I have to do is:

That all looks good. Even so, you'll want to make sure you test things thoroughly once you've performed a restore (and before making the new server live). You can use the "Preview Website" option in Virtualmin in order to test the various Virtual Servers that you've migrated before they're live.

Joe's picture
Submitted by Joe on Mon, 10/26/2009 - 15:47 Pro Licensee

You'll also want to have a full system backup handy, just in case. Whenever I do a server migration, I always realize after the move that I had some custom configuration or some tweaks in something outside of the control of Virtualmin that I need to bring over and don't remember exactly how I did it. Having a full system backup as a reference is very useful in such cases.