We've got a server running cPanel on CentOS 5.10 currently, and I'm considering whether it's worthwhile or even wise to look at upgrading to CentOS 6.4.

The server is virtualised on 2012 R2 Hyper-V, and I get the impression that CentOS 6.x has better Hyper-V support which would obviously be desirable, but that impression may be flawed.

Looking online I can't find much in the way of documentation on this subject, but some of what I can find indicates that it can be risking, and some people strongly suggest attempting a major version in-place upgrade on a production system is a very bad idea (a view I'm tempted to believe).

Fortunately in terms of testing I do have another box available. We currently have a 2nd licenced cPanel box, running the same OS version (built with the old version purely to test a recent migration from VMWare, so not currently in production), so I can use that to test things initially.

What would people say are the main dangers / pitfalls / likely problems of doing such an upgrade? Is there any real benefit to performing the upgrade (I understand 5.x will continue to be supported for a few years yet)?

closed as off-topic by Jenny D, Sven Apr 15 '15 at 7:40

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    I think you mean 6.5. I also think you're looking for this. And, cPanel being licensed by public IPv4 address is one of its most annoying misfeatures. – Michael Hampton Mar 4 '14 at 13:02
  • No, I do mean 6.4. cPanel haven't yet started supporting 6.5, so for the sake of an easy life I'll stick with what they've confirmed works. Agree about the licensing, though at least cPanel does now support NAT, as of version 11.10. – Keith Langmead Mar 4 '14 at 14:09
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    Works fine on a fresh 6.5 installation, though if you're upgrading you do have to rebuild everything because of the OpenSSL issue. – Michael Hampton Mar 4 '14 at 14:11
  • Yes that's true. That and some other settings are different dependant on when you built it, just to confuse matter. When I built the test box (same OS, same cPanel version as existing box) I noticed several changes / additions that weren't on the old install. – Keith Langmead Mar 4 '14 at 14:18
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    @Keith: Where did you read that cPanel doesn't support CentOS 6.5?! 6.4 is EoL and not suggested for production environments anymore. We've got a large number of cPanel boxes running CentOS 6.5 without any issues ... – justlovingIT Mar 4 '14 at 14:35

The main danger is that you end up with an unusable box. In fact 5.10 is still being supported so there's no need to hurry. Nevertheless we migrated several boxes from 5.x to 6.5 and noticed a slight performance increase. Besides this the new release gives you more recent kernel and package options. If that's important for you I'd consider upgrading.

Major version upgrades are a risky thing and even when you carefully check dependency issues and avoid 3rd party repos there is no guarantee that the upgrade will pass without serious issues.

While we did such in place upgrades (always take an image before doing this!) our preferred procedure now is a cPanel reinstall on a fresh RHEL/CentOS installation and then transfer the accounts using WHM's really reliable transfer accounts feature.

Start with one account for testing and if everything works well migrate the rest. Overall downtime for an account is minimized this way!

Some suggestions:

  • lower the DNS record TLL a reasonable time before you start the migration (or reroute IPs once you're done)
  • copy/set relevant settings to the target machine
  • you can also import the most important cPanel settings using a cli tool (doing the whole thing by hand takes around 20 minutes and you're sure everything is set correctly)
  • check if you have conflicting settings/customizations on the machines (e.g. my.ini customizations on the source that prevent some databases to be restored on the target machine)
  • when using roundcube with SQLite on the source server you'll have to switch the new server to SQLite before migrating the first account (otherwise you'll have to migrate afte rmigration -> more hassle)
  • migrate accounts and plans
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    Thanks for the feedback that's very useful. Considering the variety of sites hosted, using multiple components, written by a variety of developers, I think I'll play it safe and stick with 5.10, since it's hard enough at times determining what is and isn't in use at times. I'll get the second box re-installed with the latest version, and transfer some sites over (spreading the load), while keeping your suggestions in mind. At some point when there's more time I'll probably move the remaining sites and then upgrade the old box. – Keith Langmead Mar 4 '14 at 15:52

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