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OpenVZ / Virtuozzo 7 First Impressions

Odin and the OpenVZ Project announced the beta release of a new version of Virtuozzo today. This is also the next version of OpenVZ as the two are merging closer together.

There will eventually be two distinct versions... a free version and a commercial version. So far as I can tell they currently call it Virtuozzo 7 but in a comparison wiki page they use the column names Virtuozzo 7 OpenVZ (V7O) and Virtuozzo 7 Commercial (V7C). The original OpenVZ, which is still considered the stable OpenVZ release at this time based on the EL6-based OpenVZ kernel, appears to be called OpenVZ Legacy.

Odin had previously released the source code to a number of the Virtuozzo tools and followed that up with the release of spec-like source files used by Virtuozzo's vztt OS Template build system. The plan is to migrate away from the OpenVZ specific tools (like vzctl, vzlist, vzquota, and vzmigrate) to the Virtuozzo specific tools although there will probably be some overlap for a while.

The release includes source code, binary packages and a bare-metal distro installer DVD iso.

Bare Metal Installer

I got a chance to check out the bare-metal installer today inside of a KVM virtual machine. I must admit that I'm not very familiar with previous Virtuozzo releases but I am a semi-expert when it comes to OpenVZ. Getting used to the new system is taking some effort but will all be for the better.

I didn't make any screenshots yet of the installer... I may do that later... but it is very similar to that of RHEL7 (and clones) because it is built by and based on CloudLinux... which is based on EL7.

CloudLinux Confusion

What is CloudLinux? CloudLinux is a company that makes a commercial multi-tenant hosting product... that appears to provide container (or container-like) isolation as well as Apache and PHP enhancements specifically for multi-tenant hosting needs. CloudLinux also offers KernelCare-based reboot-less kernel updates. CloudLinux's is definitely independent from Odin and the CloudLinux products are in no way related to Virtuozzo. Odin and CloudLinux are partners however.

Why is the distro based on CloudLinux and does one need a CloudLinux subscription to use it? Well it turns out that Odin really didn't want to put forth all of the effort and time required to produce a completely new EL7-clone. CloudLinux is already an expert at that... so Odin partnered with CloudLinux to produce a EL7-based distro for Virtuozzo 7. While CloudLinux built it and (I think) there are a few underlying CloudLinux packages, everything included is FOSS (Free and Open Source Software). It DOES NOT and WILL NOT require a CloudLinux subscription to use... because it is not related to CloudLinux's product line nor does it contain any of the CloudLinux product features.

The confusion was increased when I did a yum update post-install and if failed with a yum repo error asking me to register with CloudLinux. Turns out that is a bug in this initial release and registration is NOT needed. There is a manual fix of editing a repo file in /etc/yum.repos.ed/) and replacing the incorrect base and updates URLs with a working ones. This and and other bugs that are sure to crop up will be addressed in future iso builds which are currently slated for weekly release... as well as daily package builds and updates available via yum.

More Questions, Some Answers

So this is the first effort to merge Virtuozzo and OpenVZ together... and again... me being very Virtuozzo ignorant... there is a lot to learn. How does the new system differ from OpenVZ? What are the new features coming from Virtuozzo? I don't know if I can answer every conceivable question but I was able to publicly chat with Odin's sergeyb in the #openvz IRC channel on the Freenode IRC network. I also emailed the CloudLinux folks and got a reply back. Here's what I've been able to figure out so far.

Why CloudLinux? - I mentioned that already above, but Odin didn't want to engineer their own EL7 clone so they got CloudLinux to do it for them and it was built specifically for Virtuozzo and not related to any of the CloudLinux products... and you do not need a subscription from Odin nor CloudLinux to use it.

What virtualization does it support? - Previous Virtuozzo products supported not only containers but a proprietary virtual machine hypervisor made by Odin/Parallels. In Virtuozzo 7 (both OpenVZ and Commercial so far as I can tell) the proprietary hypervisor has been replaced with the Linux kernel built-in one... KVM. See: https://openvz.org/QEMU

How about libvirt support? - Anyone familiar with EL7's default libvirtd setup for KVM will be happy to know that it is maintained. libvirtd is running by default and the network interfaces you'd expect to be there, are. virsh and virt-manager should work as expected for KVM.

Odin has been doing some libvirt development and supposedly both virsh and virt-manager should work with VZ7 containers. They are working with upstream. libvirt has supposedly supported OpenVZ for some time but there weren't any client applications that supported OpenVZ. That is changing. See: https://openvz.org/LibVirt

Command line tools? - OpenVZ's vzctl is there as is Virtuozzo's prlctl.

How about GUIs or web-based management tools? - That seems to be unclear at this time. I believe V7C will offer web-based management but I'm not sure about V7O. As mentioned in the previous question, virt-manager... which is a GUI management tool... should be usable for both containers and KVM VMs. virsh / virt-manager VZ7 container support remains to be seen but it is definitely on the roadmap.

Any other new features? - Supposedly VZ7 has a fourth-generation resource management system that I don't know much about yet. Other than the most obvious stuff (EL7-based kernel, KVM, libvirt support, Virtuozzo tools, etc), I haven't had time to absorb much yet so unfortunately I can't speak to many of the new features. I'm sure there are tons.

About OS Templates

I created a CentOS 6 container on the new system... and rather than downloading a pre-created OS Template that is a big .tar.gz file (as with OpenVZ Legacy) it downloaded individual rpm packages. It appears to build OS Templates on demand from current packages on-demand BUT it uses a caching system whereby it will hold on to previously downloaded packages in a cache directory somewhere under /vz/template/. If the desired OS Template doesn't exist already in /vz/template/cache/ the required packages are downloaded, a temporary ploop image made, the packages installed, and then the ploop disk image is compressed and added to /vz/template/cache as a pre-created OS Template. So the end result for my CentOS 6 container created /vz/template/cache/centos-6-x86_64.plain.ploopv2.tar.lz4. I manually downloaded an OpenVZ Legacy OS Template and placed it in /vz/template/cache but it was ignored so at this time, I do not think they are compatible / usable.

The only OS Template available at time of writing was CentOS 6 but I assume they'll eventually have all of the various Linux distros available as in the past... both rpm and deb based ones. We'll just have to wait and see.

As previously mentioned, Odin has already released the source code to vztt (Virtuozzo's OS Template build system) as well as some source files for CentOS, Debian and Ubuntu template creation. They have also admitted that coming from closed source, vztt is a bit over-complicated and not easy-to-use. They plan on changing that ASAP but help from the community would definitely be appreciated.

How about KVM VMs?

I'm currently on vacation and only have access to a laptop running Fedora 22... that I'm typing this from... and didn't want to nuke it... so I installed the bare-metal distro inside of a KVM virtual machine. I didn't really want to try nested KVM. That would definitely not have been a legitimate test of the new system... but I expect libvirtd, virsh, and virt-manager to work and behave as expected.


Despite the lack of perfection in this initial release Virtuozzo 7 shows a lot of promise. While it is a bit jarring coming from OpenVZ Legacy... with all of the changes... the new features... especially KVM... really show promise and I'll be watching all of the updates as they happen. There certainly is a lot of work left to do but this is definitely a good start.

I'd love to hear from other users to find out what experiences they have. If I've made any mistakes in my analysis, please correct me immediately.

Congrats Odin and OpenVZ! I only wish I had a glass of champagne and could offer up a respectable toast... and that there were others around me to clank glasses with. :)


( 5 comments — Leave a comment )
Jul. 2nd, 2015 07:35 am (UTC)
Does that mean VZ7 will only be available as a complete distribution and (kernel) packages for RHEL/Debian won't be provided anymore?
Jul. 2nd, 2015 01:00 pm (UTC)
take a look to wiki page about installation methods - https://openvz.org/Quick_installation
All RPM packages are available in yum repo - http://download.openvz.org/virtuozzo/releases/7.0/x86_64/
Jul. 2nd, 2015 08:44 pm (UTC)
Scott, thanks for a detailed review and for addressing some questions we haven't addressed in our release FAQ.

> Any other new features?

One pretty big feature is a switch from in-kernel ckeckpoint/restore implementation (i.e. vzcpt/vzrst kernel modules) to CRIU (http://criu.org). This is a good change as CRIU is very dynamic project of us and hopefully it will help to solve some issues people have with live migration.

[While talking about CRIU, last DockerCon 2015 session (a wrap-up) showed three demos: Docker on Raspberry Pi, Docker on IBM Z mainframe, and Quake server live migration using CRIU. Although me myself was showing something like this about 8 years ago, I was still very impressed.]

> vztt

Here is an insider story (I am more and more into history as I'm getting older). I was working on new template mgmt tools (i.e. vztt/vzpkg prototype) in 2004, then left the company in some frustration as no one was interested. I came back in 2005 to do OpenVZ revolution, and I dusted off my prototype and released it as vzpkg for OpenVZ (although I already hated working on it, as I spent so much time on it without it getting anywhere in 2004). Next thing, commercial customers asked why OpenVZ has better template tools than VZ, and other guys started working on that.

So, this vztt you see is essentially a grandchild of OpenVZ's vzpkg (with added DEB support, multiple versions of RPMS (the thing that made me stop working on it as it's very cumbersome), and other bells and whistles).

> Supposedly VZ7 has a fourth-generation resource management system
> that I don't know much about yet.


> and that there were others around me to clank glasses with. :)

Maybe you can come for LinuxCon/ContainerCon/Linux Plumbers in Seattle this August and we'll definitely do that!
Jul. 2nd, 2015 09:10 pm (UTC)
> https://openvz.org/Memory_Management_in_VZ7

Sorry, this currently doesn't describe anything, really.

The idea, in a nutshell, to build upon VSwap, adding a userspace daemon (VCMMD) which will observe resource usage and node health and dynamically change limits using some kind of heuristics. This is all I can tell right now; we will ask developers to give a better overview at that wiki page.
Jul. 3rd, 2015 01:29 pm (UTC)
"Odin and the OpenVZ Project announced the beta release of a new version of Virtuozzo today."

It is not a Beta, but alpha version. See official announce - "Virtuozzo 7 is in pre-Beta stage"
( 5 comments — Leave a comment )

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