On Sat, Aug 27, 2016 at 11:53:39AM -0400, Anthony de Boer via talk wrote: > The other thing it doesn't do is give you a bunch of virtual machines > with collectively more memory than the server has installed. I've had > to deal with a box where people had given away 110% of the RAM chips > to their various QEMU instances and the server was crawling around on > the floor in a very slow and hesitant way.
qemu/kvm supports balloon drivers in the guest. Also the host could run KMS. So you have multiple options for allowing you to overprovision the system and still do fine. > Someone mentioned options: yes, QEMU has a lot of them, and having a > script that sets the standard ones and lets you specify just what's > different between each one and the next can make starting them a lot > easier. QEMU's native commandline can easily start onto a third line on > an 80-column screen. > > Also, do please use kernel bridging and not the userspace virtual > switch. Yes a kernel bridge with tap interfaces in qemu works pretty well. There might even be better options than the tap interface these days. > If you're running a bunch of heterogenous operating systems, though, > QEMU gets you there. I've even seen people use it for Windows. > > If everything is this-decade Linux then LXC may be an option. It > isolates each VM's processes and root filesystem and network interfaces > while still sharing memory, CPUs, and (optionally, if VMs are in the same > filesystem) disk space. I've run three generations of Debian all under > the kernel that came with the latest. If you're also wanting to run eg > Fedora then there's a good chance of it just working, or if not you may > have to compare kernel configs and build a host kernel that makes > everyone happy. > > LXC lets you run collectively a far bigger party; users have access to > all the CPUs and RAM when they have a large compute job, not just the > tiny ration the QEMU config sets aside for them. So far I haven't had > to configure resource limits on LXC; YMMV. You can restrict resources with lxc as far as I recall. But you might not have to. I guess it depends if you trust the stuff inside the container to be well behaved or not. -- Len Sorensen --- Talk Mailing List [email protected] https://gtalug.org/mailman/listinfo/talk
