To answer your question, I played around with Virtualbox recently as you recall, Mark, and I had mixed results. At the time it provided to be unstable, but I found out several interesting things along the way...
As you know, full-virt solutions provide some sort of disk controller (SCSI/SATA/IDE), and these disk controllers seem to be sort of optimized for the type of physical environment that would most typically be used for the demographic of the product. For instance (and this info might be somewhat inaccurate since this is merely based on my best recollection of some of my findings at the time, or at least what some people were claiming on some mailing lists), VMWare Server does disk flushes where Virtualbox doesn't. Disk flushes are generally a good thing, but eat up a lot of I/O performance and are often ignored by many SATA disks anyway, so are often best to disable if possible (esp. in my case where my underlying file system is ZFS which has its own self-healing mechanism). The VMWare Server products in general don't seem to be too concerned about working with SATA disks or low-level consumer technology, the drivers that are available for ESXi reflect this as well.
Point being, the type of I/O performance you get with these various options seems to depend on the pairing of your hypervisor and underlying hardware. I think you are spoiled using Xen and having your VMs have (AFAIK) physical access to the disks via para-virt, because I've struggled a great deal with I/O issues on SATA disks on VMWare Server, and I'm surely not the only one! For me the key was disabling the disk flushes at the Solaris level.
I've also played around with KVM well before I played around with Virtualbox, and I found that for some reason the bridged networking changes I made via ifconfig would cease to work after a given time, not only locking me out of the VMs but of my entire host - not cool. I've been shy about giving KVM another try since then, although I probably should since it has been a while. That being said, there is something comforting to me about the hypervisor setting up your bridged networking for you! Please let me know what sort of work was involved to get bridged networking working with KVM these days, I'm curious!
I didn't even get far enough to test networking performance, but I would not be surprised if the para-virt you are doing with Xen beats out KVM there as well. However, if you were interested in getting into ethernet bonding you could probably just make up for this with providing overwhelming amounts of network bandwidth this way.
I apologize that my thoughts here are rather scattered and probably somewhat dubious, but I'm definitely interested in this topic. If I were like you and were only interested in running Linux OSes that were well suited to run as Xen guests, I probably wouldn't be in a major hurry to abandon Xen! If I didn't have such a history and affinity towards FreeBSD I might be using Xen myself :)
Mark Krenz
January 30, 2011 9:24 PM
Who on the list is using KVM based virtualization in production
environments? Any regrets? Did you use some other solution before?
I've spent the last week hard testing KVM vs. Xen and it seems that
it will work well, but there are some inefficiencies as far as network
and disk speed go, but not major enough to dismiss it.
I've been using Xen for 5 years and haven't had many gripes about its
performance. But with this recent push in the industry to KVM, I'm
getting nervous about using it in the future.
--
Joe Auty, NetMusician
NetMusician helps musicians, bands and artists create beautiful, professional, custom designed, career-essential websites that are easy to maintain and to integrate with popular social networks.
www.netmusician.org
joe@netmusician.org
Joe Auty, NetMusician
www.netmusician.org
joe@netmusician.org
