[pve-devel] vm migration + storage migration with ndb workflow notes

[Alexandre DERUMIER]

Hi,
I have finally understand the whole workflow for migrate vm + storage migrate at the same time

(I don't have to much time to work on this, maybe it's better to have stable working disk clone/copy/live mirror code before )


Here somes notes:



phase1
------
target host
-----------
create new volumes if storage != share 
---------------------------------------
add a new qm command ?


phase2
------
1)target host

send qm start to target: we need start the target vm with new disks locations.
-----------------------------------------------------------------------------
How to do this ? 
Currently the target vm read the vm config file.
Do we need to update the vmconfig file before mirroring ?
or pass drive parameters in qm start command ?

start nbd_server
----------------
nbd_server_start ip:port

add drives to mirror to nbd
---------------------
nbd_server_add drive-virtio0
nbd_server_add drive-virtio1


3)source host

start mirroring of the drives
------------------------------
drive-mirror target = nbd:host:port:exportname=drive-virtioX

when drive-mirror is finished, (block-job-complete),
the source vm will continue to access volume on the remote host through nbd

start vm migration
------------------

end of vm migration
-------------------


phase3
------
1)target host

resume vm
----------

nbd_server_stop
---------------

2) source vm

delete source mirrored volumes
-------------------------------



Other notes:
------------
How to handle migrate cancel, if drives are already mirrored, and source vm access through nbd on target host.