The first stable OpenVZ release
Posted Dec 6, 2005 1:37 UTC (Tue) by kolyshkin
In reply to: The first stable OpenVZ release
Parent article: The first stable OpenVZ release
Yes, OpenVZ uses a single kernel approach. The downsides are inability to for a VPS/guest/domain/whatever_you_call_it owner to load and use some random kernel module and, theoretically, worse stability due because of the single point of failure (in practice this can be mitigated by having a very stable kernel).
The benefits of the single-kernel approach are:
- better performance due to lower virtualization overhead;
- better memory management and resource utilization; no duplication of kernel in-memory data structures and code;
- ability to change any resources run-time (you can not instantly add some more memory to your Xen/UML guest, but it's a trivial thing to do for OpenVZ's VPS);
- better scalability (more VPSs per hardware box).
With OpenVZ, you have limits and guarantees for things such as various memory-related parameters, and a limit can be substantially greater than a guarantee, which means, if nobody else is using the resource, it can be granted to a VPS. With Xen or UML, you just can not do that.
I agree with you that that all three virtualization techniques (the third one presented by products such as VMware or QEmu) have their use cases. For OpenVZ use cases, you can check this small article.
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