[Users] Opinions and experience of Openvz

[Scott Dowdle]

Greetings,

----- Original Message -----
> Thanks CoolCold, but my question is about the risk, has you know
> openvz need a special kernel, you must to install and therefore
> update as necessary, my boos said:" that if we use openvz, when you
> upgrade from Centos 6.x, we lose the openvz kernel and leave offline
> multiple virtual machines", exist this risk?, how do you faced?

If you are talking about taking an OpenVZ EL6-based host (RHEL 6, CentOS 6, Scientific Linux 6, etc) and upgrading it to EL 7... then... no... there isn't currently an OpenVZ kernel based on the EL7 kernel.

Solution, don't upgrade from EL6 to EL7.  While there is an upgrade path for RHEL7 server (not workstation nor desktop), CentOS is working on it still on the upgrade package... and SL 7 isn't out yet anyway.

Your OpenVZ host node *SHOULD* be a very basic install without much unneeded software nor user accounts... so doing a clean install is preferred and less time consuming than an upgrade from one major EL release to the next anyway.

I believe the Parallels kernel devs are working on an EL 7-based branch of the OpenVZ kernel but I don't have any special knowledge on that nor specifics.  Like so many, I wish they'd let us know what is going on... even if they can't give a solid release date yet.

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If you are NOT talking about MAJOR release upgrades but MINOR release upgrades (for example, 6.4 to 6.5)... I have continuously upgraded my OpenVZ hosts with every minor release... starting with 6.0, 6.1, 6.2, 6.3, 6.4, and 6.5 (the current release)... and I have had no problems upgrading.  Minor version upgrades work fine... and containers work as expected.

One caveat though... you have to control your bootloader config... and if you have the stock EL kernel installed on your system... and that gets upgraded, the stock kernel will be newer than the OpenVZ one.  The stock kernel package is just called kernel whereas the OpenVZ kernel is called vzkernel.  If you have more than a single kernel installed... multiple kernels and multiple vzkernels... you need to insure that the desired kernel is default in grub.  If you don't and grub has a stock (non-OpenVZ kernel) as default... and you reboot the machine... no your containers won't work on a non-OpenVZ kernel.

Solution, don't boot to a non-OpenVZ kernel... remove non-openvz kernels completely... or if you want to keep them around for some reason... at least make sure the desired kernel is set to default in your bootloader.

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I believe I've gone through the various scenerios.  So was your boss correct in what he said... or was he/she incorrect?

TYL,
-- 
Scott Dowdle
704 Church Street
Belgrade, MT 59714
(406)388-0827 [home]
(406)994-3931 [work]