OpenVZ vs KVM vs Xen (PV and HVM) vs VMWare

[HalfEatenPie]

Alright, so we all get asked this question.  Whether it be via a support ticket or on a forum (woah!).  But unlike the other questions, this question will be different.

What's the benefits of each virtualization?  What's the negatives?  What specifically makes this virtualization shine?  What makes it fail?  Which one makes a true LEB?  Which one scales really well?

Also add on LXC vs Xen PV

 

[sundaymouse]

OpenVZ: 

Pros: CAN BE DIRT CHEAP, easy to set up and maintain.

Cons: Can be easily heavily oversold, it's a chroot container, and you don't have privacy, also direct command can be executed by node. CPU dispatch is not very ideal, an abuse user on the node can slow everyone down. Does not support many modules and functions, no Windows or BSD supported.

 

[WebSearchingPro]

I'd be more interested in LXC/Xen PV and OpenVZ to see how those three lightweight virtualization technologies compare. 

 

[remcom]

We are primarily a Xen and Vmware provider so I will just comment on VMware.

Pros:  We find the features built into the solution far exceed most other solutions. Very flexible in a clustered environment. Support is generally top notch if we ever need it and it allows us to be scalable on our cloud platform. Very easy to maintain as most items are configured upon install.  We use Dell Equallogic SANs and these integrate directly into VMware. 

VMware is a hardware level virtualization platform so it can support almost any operating system and is software friendly. 

Cons:  Can be very expensive for startups.  Would recommend Xen server for anyone with a tight budget.  Programming and integration of VMware can be painful at times.

I am sure there are other negatives for VMware but in my eyes only price is a factor as many other technologies use vmware as an example of what to do and add. 

 

[Ishaq]

I'm more interested in why this thread got a 1 star rating.

>_>

 

[Ruchirablog]

Best overall? VMware

Opensource? Xen

 

[Raymii]

I think there is no best one. It depends on what your want to do. If I need to run a few Django/rails/Java applications, I'll use openvz or a jail. Works fine, no low level bindings, high performance.


If I want a VPN server, need to run BSD, want a software based switching/routing solution or need to run windows I'll use kvm or VMWare.


If I have a lot of cash to spend and want advanced and easy HA / SAN functionality, I set up a vmware cluster.


If I have the time to set up my own cluster with for example, corosync, pacemaker, drbd/ocfs2 and nfs I'll do that and have the same functionality as the vmware cluster.


My choice mostly is KVM, because it is very flexible. For web apps however I mostly use OpenVZ.

 

[HalfEatenPie]

This wasn't really a thread based on what was the best one but rather a discussion on the benefits and negatives of each virtualization technology

Each Virtualization works best in certain situations. For example, I love using OpenVZ (if I need Linux) for my personal nodes because it helps with management and I can easily increase/decrease the hard drive space and RAM much easier than KVM.

 

[jcaleb]

can kvm ram be oversold at 2x?

 

[lifetalk]

I personally prefer OpenVZ. Why? It eliminates the unneeded overhead being just an advanced chroot, so to speak. More efficiency as opposed to truly isolated virtualization platforms.


Yes, it can be oversold and that introduces problems like stability issues and resource abuse. But if you plan things right and either oversell by a manageable amount or don't oversell at all, you can keep OpenVZ pretty happy and functioning well. Scalibility, yes. It's quite simple to upgrade/downgrade resource allocations in OpenVZ.

Whether this makes for a 'true' LEB? I don't know tbh. I'm not much of an expert when it comes to the low end market.

 

[XFS_Duke]

can kvm ram be oversold at 2x?

I think the simple answer to that is NO. It provides dedicated resources and I haven't heard of anyone being able to oversell KVM. That is one of the reasons KVM is normally more expensive...

 

[Increhost]

I think openvz is great as a provider, you can enter and fix stuff (in managed services), for the client KVM gives you

more isolation, and you can even encrypt your stuff and access via VNC to raise the FS or just leave that for

a separated partition and do it manually after boot.

Personally I don't like VMWare as the manager needs some special enviroment to work,

we rather prefer Web Management, to be able to access it from everywhere anytime.

The experience with VMWare was on a client who requested using ESXi but it's

more a personal choice not to use it

Cheers!

 

[perennate]

@Increhost if something is good for the client I'd say it's also good for the provider.

 

[DragonDF]

I like VMWare in my PC running Windows XP. \o/

In server, I think the price is something people will think a lot before start to use.

KVM is a good option for Windows' servers.

 

[Enterprisevpssolutions]

I think the simple answer to that is NO. It provides dedicated resources and I haven't heard of anyone being able to oversell KVM. That is one of the reasons KVM is normally more expensive...

Yes Kvm can oversell memory but the cpu load increases the more you oversell the ram, more on this can be found HERE

Is dynamic memory management for guests supported? 

This is a broad topic covering a few areas.

 

Certain guests (only Linux at the moment) have a balloon driver, so the host can have the guest allocate a certain amount of memory which the guest won't be able to use anymore and it can then be freed on the host. Ballooning is controlled in the host via the balloon monitor command.

 

Some hosts have a feature called KSM (Kernel Sharedpage Merging), which collapses together identical pages; this requires kernel support on the host, as well as a kvm new enough to opt in to the behavior. As some guest platforms (most notably Windows) zero out free'd memory, such pages are trivially collapsed. The ksmctl command needs to be used to enable KSM; alternately, the ksmtuned service found in Fedora 12 can be run to dynamically adjust KSM's aggressiveness based on the amount of free memory available.

 

Balloon feature in kvm has been known to allow over allocation of 80% or more on memory again the more you allocate the more cpu load you are using as the node is trying to keep up with the request for memory to all the vps.  

 

[Ruchirablog]

more on this can be found HERE

copied from buyvm wiki? http://wiki.frantech.ca/doku.php/openvz_vs_kvm

 

[peterw]

can kvm ram be oversold at 2x?

Yes you can: Best practice KVM over-commit memory resources by using page sharing or ballooning.

 

[Aldryic C'boas]

@Enterprisevpssolutions - that article you linked was written by a kind contributor especially for our wiki.  Care to explain why you're ripping our wiki content without our consent for your own use?

 

[Enterprisevpssolutions]

@Enterprisevpssolutions - that article you linked was written by a kind contributor especially for our wiki.  Care to explain why you're ripping our wiki content without our consent for your own use?

Not stolen shared for knowledgebase http://creativecommons.org/licenses/by-nc-sa/3.0/ is located on your site. The same information is found on other sites and not all sites have uptime or get taken down and many articles can get lost. We look at articles and modify them or add them to our knowledgebase for storage, sharing and Security of data. If you do not want us to have this please let us know and we can take it down it does have the source of the info at the bottom of our page.  If we are wrong please let me know and I will talk to our team to have it removed.

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[Aldryic C'boas]

It has "source info" because you just added that line.  You are also not using the article non-commercially - so yes, pulling the content from our wiki for use in your own knowledgebase is straight theft.  Have the decency to either write your own content, or ask for contributions, rather than steal from others.