On 22.07.2020 19:30, Peter Xu wrote:
On Wed, Jul 22, 2020 at 06:47:44PM +0300, Denis Plotnikov wrote:
On 22.07.2020 18:42, Denis Plotnikov wrote:
On 22.07.2020 17:50, Peter Xu wrote:
Hi, Denis,
Hi, Peter
...
How to use:
1. enable background snapshot capability
virsh qemu-monitor-command vm --hmp migrate_set_capability
background-snapshot on
2. stop the vm
virsh qemu-monitor-command vm --hmp stop
3. Start the external migration to a file
virsh qemu-monitor-command cent78-bs --hmp migrate exec:'cat
./vm_state'
4. Wait for the migration finish and check that the migration
has completed state.
Thanks for continued working on this project! I have two high level
questions
before dig into the patches.
Firstly, is step 2 required? Can we use a single QMP command to
take snapshots
(which can still be a "migrate" command)?
With this series it is required, but steps 2 and 3 should be merged into
a single one.
I'm not sure whether you're talking about the disk snapshot operations, anyway
yeah it'll be definitely good if we merge them into one in the next version.
After thinking for a while, I remembered why I split these two steps.
The vm snapshot consists of two parts: disk(s) snapshot(s) and vmstate.
With migrate command we save the vmstate only. So, the steps to save
the whole vm snapshot is the following:
2. stop the vm
virsh qemu-monitor-command vm --hmp stop
2.1. Make a disk snapshot, something like
virsh qemu-monitor-command vm --hmp snapshot_blkdev drive-scsi0-0-0-0
./new_data
3. Start the external migration to a file
virsh qemu-monitor-command vm --hmp migrate exec:'cat ./vm_state'
In this example, vm snapshot consists of two files: vm_state and the disk file.
new_data will contain all new disk data written since [2.1.] executing.