2017-08-30 11:40 GMT+02:00 Fam Zheng <f...@redhat.com>: > On Wed, 08/30 11:16, Vincenzo Romano wrote: >> 2017-08-30 10:53 GMT+02:00 Fam Zheng <f...@redhat.com>: >> > On Wed, 08/30 08:17, Vincenzo Romano wrote: >> >> Il 30 ago 2017 05:19, "Fam Zheng" <f...@redhat.com> ha scritto: >> >> >> >> On Tue, 08/29 18:32, Vincenzo Romano wrote: >> >> > I'd like to move away from "another virtualization solution" to QEmu. >> >> > I've more or less all the needed bits in my hands in order to define, >> >> > run and manage QEmu VMs. >> >> > What I am missing is the knowledge of how to backup a live VM. >> >> > Of course, if I shutdown the VM, I can simply copy its files and the >> >> > startup script on another QEmu host. >> >> > But my main objective is to do the backup while the VM is running. >> >> > I think I could use the snapshot feature, but have no idea on how to >> >> proceed. >> >> > Any hint? >> >> >> >> In short, just do what libvirt would do: use QMP and send 'drive-backup' >> >> command. >> >> >> >> This is a very good howto: >> >> >> >> https://github.com/qemu/qemu/blob/master/docs/interop/live-b >> >> lock-operations.rst >> >> >> >> Fam >> >> >> >> >> >> Thanks. >> >> I presume there's a 'drive-restore', though I need to look better in the >> >> docs. >> >> >> >> Is there any side effect in case the CPU where the VM will be restored is >> >> not exactly the same as the one where the VM got backed up? >> > >> > No, there isn't a 'drive-restore'. 'drive-backup' only takes care of the >> > disks, >> > so the CPU, ram and device states aren't saved. >> > >> > If you boot from the backup image, CPU and ram are restarted from powered >> > off >> > state, so what happens is effectively like a power loss at the point of >> > 'drive-backup': anything not saved to disk are lost. >> > >> > Fam >> >> I understand. >> >> So, if I haven't miunderstood, at the moment QEmu-KVM doesn't >> implement "VM snapshots". > > It does. There are "savevm" and "migrate" (or "migrate -b") that can save the > CPU/ram etc: > > https://www.linux-kvm.org/page/Migration#savevm.2Floadvm_to_an_external_state_file_.28using_pseudo-migration.29 > > Fam
Thanks again, Fam. So I should issue both QMP commands, in theory, with the VM in a frozen state. Right? -- Vincenzo Romano - NotOrAnd.IT Information Technologies -- NON QVIETIS MARIBVS NAVTA PERITVS