OS Virtualization Interview

VirtualizationBuff writes "KernelTrap has a fascinating interview with Andrey Savochkin, the lead developer of the OpenVZ server virtualization project. In the interview Savochkin goes into great detail about how virtualization works, and why OpenVZ outshines the competition, comparing it to VServer, Xen and User Mode Linux. Regarding virtualization, Savochkin describes it as the next big step, 'comparable with the step between single-user and multi-user systems.' Savochkin is now focused on getting OpenVZ merged into the mainline Linux kernel."

Comments

Re:Virtualization is the future

[ovz_kir]

Speaking of complexity, it is indeed complex. Any OS is complex. VMWare itself is very complex. Any stuff that is not trivial is complex.

The questions are: whether it works, and is it maintainable?

Whether it works? OpenVZ and Virtuozzo works just fine -- ask anybody who's using it, get a cheap Virtuozzo VPS from one of the HSP, or just install it on your Linux box and see for yourself.

Is it maintainable? OpenVZ stable kernel is based on Linux kernel 2.6.8 (with tons of backported fixes and driver updates). We have recently ported it to 2.6.15 and 2.6.16, and also to the kernels from Fedora Core 5 (here) and SUSE 10 (here). So I think it is maintaintable.

[VMWare] has some performance issues, and Xen's paravirtualization gets a fine balance, that is to have a minimal set of modification of the guest OS.

Hmm, isn't that Xen which requires a modified Linux kernel? Is that "a minimal set of modifications"? Are you kidding? In contrast, in OpenVZ's VE you run an unmodified Linux distribution, the only missing piece is the kernel which is provided by the host OS. There are modifications (like removing getty from /etc/inittab), but they are not strictly required.

What's the point then? OpenVZ also runs a modified Linux kernel. Well, the point is you can not have hundreds of VMs with Xen (or VMWare), but you can -- with OpenVZ. OpenVZ is also more stable -- but Xen will cure this, I believe, so this is not the point in the long term.

Basically, VMWare is at the one end of the scale -- can run anything, bad performance, scalability and density, OpenVZ is on the other end -- can run Linux 2.6 only, native performance, best possible scalability and density, easier management. Xen is somewhere in the middle of all this.