Web Hosting Talk : Web Hosting Main Forums : VPS Hosting : Xen vs OpenVZ

[ichilton]

Hi,

I'm interested in hearing thoughts on OpenVZ vs Xen for web hosting - from the point of view of both a host and a user?

Which is better / faster / more reliable / easier to maintain?

Thanks,

Ian

[MikeDVB]

They both have their pros and cons. It really depends on what you want to do and how you want to do it as to which one will work for you.

I can equate your question to asking "Which web hosting provider is the best?" ... there is no "best" but only the one that is best for you and your particular needs.

If you can tell us what you want/plan to do we can likely give you better advice.

[Crothers]

I prefer OpenVZ, custom OpenVZ control panels have the ability to do so much more in my opinion.

Also OpenVZ is more "native" speeds, then Xen.

Also, if you have a VPS, do you "Really" need to have a custom kernel?

[devonblzx]

Originally Posted by Crothers

I prefer OpenVZ, custom OpenVZ control panels have the ability to do so much more in my opinion.

Also OpenVZ is more "native" speeds, then Xen.

Also, if you have a VPS, do you "Really" need to have a custom kernel?

Xen provides better isolation and dedicated memory, OpenVZ uses a shared kernel approach so resources are more shared.

This provides benefits for both, users are "less" likely to affect others in Xen due to not being able to oversell and more isolation however it can still happen especially with disk i/o.

OpenVZ is faster as stated because it requires less overhead with the shared kernel approach but overselling can give its advantages and disadvantages. The obvious, overselling can cause poor speeds which is why OpenVZ has a bad rep around here because too many hosts oversell.

I'd say OpenVZ also has much better documentation and ease of use.

[QuickWeb-Roel]

You may also have a look about this recent thread about the topic here: http://www.webhostingtalk.com/showthread.php?t=912557

heaps good insights from experienced Linux Admins.

[Matt - Kerplunc]

OpenVZ you can oversell, Xen you can't
Xen has a lot more operating system options (With HVM-ISO), where OpenVZ is just things running the same linux kernel
Both have fantastic control panels (personally i prefer SolusVM which supports both OpenVZ and Xen)
I find the CLI tools with OpenVZ a lot easier to use then Xen, but i'm just learning the Xen ones currently

[Nnyan]

You can search these forums and see this topic discussed numerous times. I like Xen myself but I have never had any issues with OpenVZ host that was related to the technology. Quality hosts manage their servers properly so I never had a problem.

[BlaZeX]

I'd choose OpenVZ It is much more easy for customizing & operating

[tsj5j]

Quick Summary.

Xen = paravirtualization (virtualizes the kernel) vs OpenVZ = OS-level virtualization
As a result, Xen is more flexible but OpenVZ has lesser overhead.

Xen = true memory accounting with swap vs OpenVZ = accounting memory allocated
As a result, OpenVZ often over accounts for RAM that is allocated and not used.
For example, a java application will likely fail in a 512MB OpenVZ container but succeed in a 128MB Xen container as java loves to allocate alot of memory.
Furthermore, OpenVZ permits (and makes it easy to) overselling, Xen does not.

[danceboysf]

Originally Posted by tsj5j

Quick Summary.

Xen = paravirtualization (virtualizes the kernel) vs OpenVZ = OS-level virtualization
As a result, Xen is more flexible but OpenVZ has lesser overhead.

Xen = true memory accounting with swap vs OpenVZ = accounting memory allocated
As a result, OpenVZ often over accounts for RAM that is allocated and not used.
For example, a java application will likely fail in a 512MB OpenVZ container but succeed in a 128MB Xen container as java loves to allocate alot of memory.
Furthermore, OpenVZ permits (and makes it easy to) overselling, Xen does not.

What happens when a given OpenVZ host doesn't oversell and doesn't offer burst RAM over OpenVZ ? I use one host here with nice CPU-intensive application that loves to eat all the ram (like java), and still no memory conflicts and corruption (app. uptime = 25 days now). Other OpenVZ's offen cause my app to get corupted and fail over time. Over Xen this specific application causes almost any host to kick me out (i didn't seen a host that will tolerate 25% load of a HT CPU core for constant period).

[ichilton]

Hi,

Thanks for the replies.

What i'm wanting to do is Apache, MySQL and PHP web hosting - separate sites out across multiple VM's rather than virtual host them on the same server.

Which is most suited to that?

Which is going to give the best performance?

What's going to happen if a site comes under high traffic under both of them?

Does not having swap not cause a problem for OpenVZ? - doesn't it start running out of memory and fall over?

Thanks,

Ian

[VirtualSRV]

OpenVZ is generally the most cost effective solution for virtualization.

Your hosting needs are pretty standard, you dont need custom kernel hence my advice is you should go for OpenVZ.

OpenVZ is basically faster than Xen when not oversold and when high memory swap is not required.

[suhailc]

I'd also say a big consideration is that if you're managing VMs yourself use OpenVZ.

For unmanaged VMs, Xen offers true isolated virtual partitions, so even if someone tries to wreck it, it doesn't affect everyone else on the same server.

[beastserv]

you might want to look at this thread also, this is a real live case of someone who got his VPS down due to another "bad user" on the same hardware node.

http://www.webhostingtalk.com/showthread.php?t=928090

the true answer is - whatever is easy for you to manage would be the best choice all do the same basic job :-)

[tsj5j]

Originally Posted by danceboysf

What happens when a given OpenVZ host doesn't oversell and doesn't offer burst RAM over OpenVZ ? I use one host here with nice CPU-intensive application that loves to eat all the ram (like java), and still no memory conflicts and corruption (app. uptime = 25 days now). Other OpenVZ's offen cause my app to get corupted and fail over time. Over Xen this specific application causes almost any host to kick me out (i didn't seen a host that will tolerate 25% load of a HT CPU core for constant period).

I think you completely misunderstood the differences when I stated.

I said that the same application with high allocative tendencies (eg. java) will reflect a much higher memory usage in OpenVZ compared to Xen, meaning you need to upgrade to a higher plan = more money lost.
This does not mean that OpenVZ is less reliable.

And, whilst Xen doesn't allow overselling, it does allow you to put 16GB RAM on say, a Pentium III processor. So naturally it isn't overselling but your performance is still crap.

Hence, if the same host offers Xen and OpenVZ at the same time, I'd go for Xen without a second thought.
But if a crap host offers Xen and a reputable host offers OpenVZ, I'd still go for OpenVZ.