v3 comes with a new QMP command drive-mirror, an improved blockdev-snapshot-sync that just reuses transaction functionality, and a new image creation mode enum. I also tested that the command can be used to migrate without shared storage.
Tested with the following scenarios: a) mirror only 1) create base.qcow2 and starat QEMU with it 2) Execute the following QMP command { "execute": "qmp_capabilities" } { "execute": "transaction", "arguments": {'actions': [ { 'type': 'drive-mirror', 'data' : { 'device': 'ide0-hd0', 'target': '/home/pbonzini/mirror.qcow2' } } ] } } { "execute": "cont" } 3) hibernate the guest (this requires an IDE disk and -cpu kvm64,-kvmclock) 4) restart the guest with mirror.qcow2 b) Same as (a) with drive-mirror command. c) streaming to new image 1) start QEMU with an existing image test.img 2) execute the following HMP commands drive_mirror -s ide0-hd0 /home/pbonzini/mirror.qed qed block_stream ide0-hd0 3) shut down the guest (sorry, this took a looong time and I forgot to hibernate here) 4) move away the base image 5) restart the guest with mirror.qed d) atomic snapshot+mirror (QMP only): 1) start QEMU with an existing image test.img 2) Execute the following QMP command { "execute": "qmp_capabilities" } { "execute": "transaction", "arguments": {'actions': [ { 'type': 'blockdev-snapshot-sync', 'data' : { 'device': 'ide0-hd0', 'snapshot-file': '/home/pbonzini/base.qcow2' } }, { 'type': 'drive-mirror', 'data' : { 'device': 'ide0-hd0', 'target': '/home/pbonzini/mirror.qcow2' } } ] } } { "execute": "cont" } 3) hibernate the guest (this requires an IDE disk and -cpu kvm64,-kvmclock) 4) check that mirror.qcow2 has test.img as the base 5) restart the guest with base.qcow2 6) restart the guest with mirror.qcow2 v2->v3: replace reuse argument with NewImageMode enum and mode argument; renamed all commands and actions; implemented blockdev-snapshot-sync in terms of group snasphots; added new drive-mirror command and HMP equivalent. Marcelo Tosatti (1): Add blkmirror block driver Paolo Bonzini (7): fix format name for backing file qapi: complete implementation of unions rename blockdev-group-snapshot-sync add mode field to blockdev-snapshot-sync transaction item qmp: convert blockdev-snapshot-sync to a wrapper around transactions add mirroring to transaction add drive-mirror command and HMP equivalent Makefile.objs | 2 +- block/blkmirror.c | 239 +++++++++++++++++++++++++++++++++++++++++++++ blockdev.c | 232 ++++++++++++++++++++++++------------------- hmp-commands.hx | 31 +++++- hmp.c | 34 ++++++- hmp.h | 1 + qapi-schema-test.json | 10 ++ qapi-schema.json | 119 ++++++++++++++++++---- qmp-commands.hx | 105 +++++++++++++++----- scripts/qapi-types.py | 5 + scripts/qapi-visit.py | 31 ++++++- test-qmp-input-visitor.c | 18 ++++ test-qmp-output-visitor.c | 34 +++++++ 13 files changed, 707 insertions(+), 154 deletions(-) create mode 100644 block/blkmirror.c -- 1.7.7.6