* Stephen Gregory <oclug [ at ] kernelpanic [ dot ] ca> [070408 23:43]: > I am considering Qemu + kqemu to run a couple of virtual Linux > machines. The host and virtual machines will be Debian/Etch. Does > anyone have any experience with Qemu and kqemu? Did you run into any > problems? What is the performance like? How does it compare to Xen? kqemu can be an order of magnitude faster for some tasks then qemu, but still a bit slower then xen. kqemu is a lot easier to setup then xen. > I have used Xen in the past. Unfortunately the Debian/Etch Xen Linux > kernels require PAE support which my hardware does not appear to > have. I would rather not compile and manage my own kernel images or > rely on 3rd party kernels. Similarly OpenVZ looks good but there are > no Debian kernels. - qemu does emulation of the CPU. - qemu w/ kqemu does full virtualization. Guest OS is unmodified. - Xen does para vitalization (and some full virtualization now). Guest OS is aware that it's running under Xen. - OpenVZ and Vserver do compartmentalization. There is only one kernel. The above list is sorted by increasing performance. Emulation sucks for performance. Horribly. IO sucks. CPU sucks. RAM gets eaten. All virtualization solutions hurt IO performance more then CPU performance. It eats your RAM. Compartmentalization has very little overhead on CPU and IO -- close to none. It consumes more RAM, but to a lesser degree then emulation and virtualization, because there is one kernel. It depends on what you need. Compartmentalization is the least secure, and the most intrusive if you have a kernel crash, because there is only one kernel. WRT security the above list goes from qemu being most secure to OpenVZ/Vserver being the least. > I considered VServer but it looks messy. The howtos I have read all > seem more complicated then the Qemu + kqemu howtos. Also there seems > to be a few quirks, particularly with the networking. If I am wrong > please convince me. VServer is probably better as my host machine > does not have much ram. Compartmentalization is definitely a good choice if you don't have enough RAM. I have been running vserver for some time and I've been pretty happy with it. It's a lot easier to setup vserver from scratch then xen. I haven't tried to do it the debian way, but I saw there is some support for it. -Bart -- WebSig: http://www.jukie.net/~bart/sig/