What are the benefits for running kvm instead of virtualbox?
Most of the threads that I've read said that using kvm affects performance. So whaat are the benefits

They are always in a close race but I'd still think that KVM is a bit faster. http://www.phoronix.com/scan.php?pag...4_kvmbox&num=1

That assumes fully supported host OS and hardware. As hardware and vm technology improves they get to claim better speeds, more features and ease of use, better admin features too.

You can't go wrong with either choice I'd think. For server farm you may be better off with kvm but that is only a guess.

try to manage a large number of hosts and a very large number of VMs and you won't be asking this question.

you wanted to say that, compared to VMware, Virtualbox is more like VMware Workstation and KVM more like ESXI?

if you want an exact comparison, kvm, the linux kernel, libvirt and virt tools are like ESXi, kvm on it's own is closer to vmkernel only. As for myself, I have said what I wanted to say.

Unlike ESXi, you don't need to connect remotely to access the VMs with KVM. VirtualBox is very easy to use, seems to be between VMware Player and Studio in it's functionality. VirtualBox is also a rather high level application compared to KVM. This can mean a great deal in performance.

If you want something easy to use, use VirtualBox.
If you're willing to learn how to use it, KVM can leave VirtualBox in the dust.

VirtualBox also has some interesting features like being able to record the VM's screen, even when the resolution changes. I know first hand how hard it is to record VMs without that. VirtualBox also allows you to resize the guest display by resizing the window itself.
And another cool feature of VirtualBox:
http://www.howtogeek.com/171145/use-...rtual-machine/

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> VirtualBox also allows you to resize the guest display by resizing the window itself.

Also possible with KVM and Spice

been doing this for years with X-Windows. oh wait ... some people call that "remote" so i guess it doesn't count.

Let's not forget that VirtualBox is an Oracle product - the Oracle corporation could decide anytime to stop support/development of VirtualBox and at that point you would have to hope that somebody forks it in some intelligent way, or otherwise you would have to re-implement everything.

We had & have a similar situation with MySQL:
MySQL was bought by Oracle and the original MySQL was forked into MariaDB => people are migrating to MariaDB.
I am one of those that is migrating and I do enjoy the additional functionalities of MariaDB and so far I did not have any problems.

Well, independently if you use KVM or VirtualBox, you're adding at least an additional layer between your HW and SW - impossible that this does not affect negatively the performance.

One thing that you should definitely investigate, if you need it, is the area of rendering/graphics/3Dgraphics running within the VM.
I don't have experience with it, but it could be that VirtualBox performs much better than KVM in this area.

not necessarily, since KVM can use para-virtualized drivers if available, giving the guest direct access to the hardware. If you can set up your guest with these, it is about as quick as on native hardware. I'm not sure if VB can do this.

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@dt64

If you're referring to PCI-passthrough:
you need a GPU allocated uniquely to that specific VM + the PCI-bus of the GPU not being used for anything else (reserved during kernel boot through parameters) + VTx enabled on the CPU and BIOS + VTd enabled on the motherboard and BIOS => I've done it once and it does work but it's a lot of work and ends up being a very specific setup that you cannot just fire up spontaneously for any VM.

Contrary to popular belief of VirtualBox having some kind of performance impediment - it has far better guest hardware support than anything else so (and I have checked myself) you should find if you configure the extras that VirtualBox has available, it will be hard to beat (I have run benchmarks on the guest OS). That is if you care about the actual performance of the VM itself. There is a lot of acceleration available and I have found nothing that can match it from a "logging into the VM and using it" point of view. That being said, it depends on what you use the VMs for.

One caveat is that this is probably more true if you run Windows operating systems on the VMs (I use Linux as host and run my Windows machines as VMs within).

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PV is great, but it also doesn't lack some overhead. The general idea really is that the existing hardware is way too powerful for a single workload, and VMs allow us to safely exploit the hardware to the fullest, even if some of the performance is lost on the way.

This isn't PCI passthrough, this is GPU passthrough, and it's quite simple with vfio. Regular PCI passthrough is even simpler, no rocket science there

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can you please be more specific? better guest hardware support - what does that mean?

So have I, there is a reason KVM is at the top of specvirt every year since 2009.


more specifics please

This should not matter. KVM was developed with windows in mind