On Thu, Jan 20, 2011 at 01:53:25PM -0600, Renich Bon Ciric wrote: > Hello guys! > > I'm in direct contact with the guys @ CloudSigma. > > I've asked them to support CPU, RAM and HDD hot swapping and they say > their system is capable of this but that linux (particularly, Fedora) > isn't. > > They agree to do some testing on the subject but, honestly, I don't > consider myself to be sufficiently knowledgeable to lead this. > > Is there anybody here interested on this? > > Anyway, their lead dev told them this: > > "Libvirt doesn't do any of this stuff itself (hot swapping). What it > does include is > an ability to use the virtio balloon driver. This essentially allows you to > give a guest a large amount of ram, with it then voluntarily lending some of > that memory back to the system. It requires a degree of cooperation and > trust between host and guest that isn't appropriate (or easy to bill) in a > public cloud, but it's a useful hack on private VM deployments in the > absence of proper memory hotswap in qemu-kvm." That is correct. The live memory adjustment for KVM/QEMU via libvirt is ballooning, not memory hotplug. Likewise for Xen and VMWare. Real memory hotplug is a future RFE. > I've read some stuff here: > http://www.linux-kvm.org/page/CPUHotPlug Yep, CPU hotplug is available for KVM/libvirt, but support among common guest OS is flakey. It doesn't work at all for Windows, and for Linux only hotplug works, but not unplug. Xen however did allow hot-unplug because it was using a different mechanism IIUC. For KVM, HDD hotplug already works for virtio disks, or SCSI disks, or USB disks. It doesn't work for IDE disks. For Xen hotplug works for xen paravirt disks. For KVM, NIC hotplug also works, and in general any kind of emulated PCI device can be hotplugged. For Xen, again their xen paravirt NICs could be hotplugged. Daniel _______________________________________________ cloud mailing list cloud@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/cloud
