Linux Kernel Virtual Machines

I've been running KVM for a few of the management servers at work, I've actually been very happy with it all around, and now want to move to the next phase, and deploy some heavy services (data-mining, ETL, etc) onto them.

I was wondering if anyone here has used KVM for something serious and has had any issues or comments.

I'm specifically interested in performance-related issues you've experienced (assuming that you've not had stability issues to begin with.

Formulating this for Q&A...

1. Have you run KVM to host a resource-heavy service?
2. If Yes to 1, have you had any stability issues?
3. If Yes to 1 and No to 2, have you had any performance issues?

(When I get around to it, and I will eventually, I will push one of my LVMs into a very loaded (non-prod) environment, and I'll let you all know how it goes. The data mining services we run are as heavy as it can get, so I'm sure this test will be fruitful! =) - Meanwhile I'm still looking forward to more answers to the questions above from anyone who'd like to share. And big thanks to everyone who's responded so far.

Solution 1:

Personally, I haven't used KVM for anything else then my personal experiments (yet). But in case you are wondering whether KVM is ready for prime time: Red Hat seems to think so.

That said, since there are no enterprise ready distributions as of yet that implement kvm, I doubt you'll find a lot of people who have actually run kvm in heavy production. However, I am pretty sure me and my colleagues are going to look into kvm as soon as RHEV is launched. The technology is too promising to ignore.

Solution 2:

So far I've only used KVM for small scale personal use VM's so I can't help you on that front.

If you find you're having performance issues with KVM, you should try installing with the virtio drivers enabled. I've found the VM to be significantly more responsive with the faster I/O.

Solution 3:

I have used KVM on my laptop (some intel core2duo with 2GB RAM), for packaging and compiling applications I don't think that counts as resource-heavy, but i can have been running concurrent 4 VMs full time doing different sorts of compile/packaging/apache i had no stability issues, excpt for when the host CPU was consumed, then some VMs would report errors about clock and get too slow, but a restart of that VM fixes it

virtio is good if you get passed booting the vms with it. and generally it is good to separate the VM disks from each other try to use a drive for each VM or LVM/Raid for the disks i recommend to avoid the file disks