Which one is the best performance? OpenVZ, XEN or KVM?

yumiVPS · November 2011

NO over sell

Boltersdriveer · November 2011

If you're looking for a platform with a less chance of overselling, that'd be Xen. But the providers are still able to oversell on hard disk and RAM.

Rens · November 2011

Xen. We have tested with KVM, but are not getting anywhere near the results we get with Xen. It is improving fast so we are keeping an eye on the developments.

I would not consider openvz, although most of the problems are created by overselling.

rds100 · November 2011

If not overselling, OpenVZ should provide the best performance since there is almost no virtualization overhead compated to bare metal server.

marrco · November 2011

Overselling is good. Excessive overselling is not. It's quite stupid to charge a lot more and leave unused resources on the node. Overselling can help keeping prices low while providing a great performance.

maybe for java game servers or bitcoin mining one full cpu and 100% of your allocated ram are necessary, but for standard website hosting, rsync backup, monitoring services etc. you usually need just a small part of your resources and for limited time.

maybe providers could offer 0 overselling for minecraft/torrenting/tor proxy on dedicated nodes with a higher price, and honest overselling at at much lower prices for users that have different needs.

LivingSouL · November 2011

@marrco said: but for standard website hosting, rsync backup, monitoring services etc. you usually need just a small part of your resources and for limited time.

Good point. If you're on the same node with users who runs gameservers.. your site will go slow.. LOL

marrco · November 2011

@LivingSoul that's why sometimes less is more for me. I check for restriction like no irc, no torrenting, i prefer hosts that offer less traffic and space, i check if the 'owners' are just some kids trying to sell part of new dedi gaming server or a (company/adult/startup) trying to get in the VPS business.

Providers choose their market. Some take all, some try to appeal to gameserver users other have a different target. I'm also very suspicious of high discounts, 20% is enough. Want more? Prepay 6 months and one is free. Or pay one year and have 2 free months.

But price and listed resources are just a part of the story. Company background and owners experience can tell you more about the ability to manage overselling. And when my brochure websites are slow and i complain to the provider, they sometimes choose to keep me as a customer (and move gameservers/ircers and other l33t users on a separate node).

LivingSouL · November 2011

I agree.. :)

bobinfo · November 2011

@Rens said: Xen. We have tested with KVM, but are not getting anywhere near the results we get with Xen. It is improving fast so we are keeping an eye on the developments.

Xen PV I guess? What about Xen HVM vs KVM?

Infinity · November 2011

I'd choose KVM over HVM. PV does have a performance edge over both of those due to less overhead etc.

Rens · November 2011

@bobinfo: Both, especially disk performance was a problem with KVM. On some hypervisors we also did not get proper test results (speeds above what was possible).

Aldryic · November 2011

Performance aside, I prefer KVM from a security standpoint. With OpenVZ, all an admin has to do is 'vzctl enter' to get into your VPS as root, or simply browse /vz/private/'ctid'. With KVM, so long as you reset your root pass (or disable root) after provisioning, they would have to SU the container to get into it. Aside from the obvious 'downtime' from this, you can also set on-boot scripts to email you when your VPS starts, etc, to let you know if it's been rebooted.

dmmcintyre3 · November 2011

@Aldryic said: Performance aside, I prefer KVM from a security standpoint. With OpenVZ, all an admin has to do is 'vzctl enter' to get into your VPS as root, or simply browse /vz/private/'ctid'. With KVM, so long as you reset your root pass (or disable root) after provisioning, they would have to SU the container to get into it. Aside from the obvious 'downtime' from this, you can also set on-boot scripts to email you when your VPS starts, etc, to let you know if it's been rebooted.

Also, if the host does that and then tries to login, it won't bypass most login detection scripts like vzctl enter {ctid} does. But, if you leave the console logged in when you are not using it, then they have an easy way in.

Aldryic · November 2011

@dmmcintyre3 said: But, if you leave the console logged in when you are not using it

Aside from a VPS where I want to block SSH completely, I don't use console at all after the initial setup :P

MrAndroid · November 2011

@rds100 Correction, with OpenVZ there is no overhead.

OpenVZ will provide the best performance as if it was running outside of it, but it depends on the settings, as well as what's running on the node and it's load

bobinfo · November 2011

@Rens said: Both, especially disk performance was a problem with KVM. On some hypervisors we also did not get proper test results (speeds above what was possible).

With KVM the disk can't be a LVM 'partition'? In that case there is no overhead, right?

Infinity · November 2011

@bobinfo said: In that case there is no overhead, right?

No noticable overhead.

ghost · November 2011

from 2.6.39 / 3.0 , XEN inside to kernel too, you can choice to keep use XEN.

vtw · January 2012

Is it true that you'll use less RAM on KVM than on OpenVZ when running the same programs? Why/How if true?

Francisco · January 2012

@vtw said: Is it true that you'll use less RAM on KVM than on OpenVZ when running the same programs? Why/How if true?

Sometimes.

OpenVZ used to allocate RAM based on the virtual size, not based on what was actually being used. This bug/derp is addressed in the new 2.6.32 based kernels.

In 2.6.32 RAM is allocated the same was as KVM/XEN/vmware/etc

Francisco

PowerChaos · January 2012

it depens on what you want to run on it

i personal preffer XenServer ( bare metal based on Xen) because ram overselling is not possible ( disk overselling is not possible eather)

it depends to what you like to do, do you want to spend on dedicated harware and provide true virtual dedicated servers ( where everything is 100% isolated from each other) or do you preffer to run things in a container ( shared ram with allocated max ram usage ?)

Xen allocates the ram and isolate the ram so only that certain vps can use the assigned ram for 100% when openvz use a container and let you use up to XX ram , but the ram stays shared (allows overselling as the ram is always free )

so to give a example about this if you got 3 vps servers with each 1GB ram , your node is 4GB ram then on Xen you got 1GB ram free that get used by the core for stability, and 3GB ram that get serperate used by the vm's

on Openvz you still got 4GB ram free that get used by the system and the vm's just take up to 1GB ram as soon they need it , the first who need it get it that makes it that on openvz you can use 3 vps servers with 2GB ram and still works perfect

only problem , if all 3 vps servers are requesting for 2GB ram at the same time then you get a big crash ... thats what overselling does

so to get back on the normal request , i preffer Xen because of his dedicated ram assignment

Greetings From PowerChaos

Breezehost · January 2012

Xen is far better than OpenVZ as all the resource that a VM have, are allocated dedicatedly to the VM. So basically, the RAM and disk space you have in your Xen VM, Well, although not 100% is dedicated resources

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Which one is the best performance? OpenVZ, XEN or KVM?

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