Warm migration with shutdown/startup in a specific timeframe

[gdelafond]

Warm migration with shutdown/startup in a specific timeframe

[olivierlambert]

And if it's not possible to do it between 2 and 4AM because it's longer than this, what should be the behavior?

[gdelafond]

In my mind, the only pre-requisite was to have already done 2 sync : the first one and one delta. Once it has been done launch the last sync in the timeframe (even if it took longer than the duration timeframe).

Maybe we could have an option to cancel the migration if the last delta sync was longer than the timeframe? but it is more complicated and the sync time can vary.

My idea at the beginning was: "start a warm migration, but try to make the shutdown at the best moment for my customers".

First example:

    fs1          fe1    d1         d2         d3         d4  E     
--+-+--------+----+-----+----------+----------+----------+---+------+ 
20h        21h        22h        23h         0h         1h         2h
                                                        [ timeframe ]

fs1: warm migration start => start the full first copy
fe1: first sync end
d1: 1st delta sync
..
repeat delta sync until the timeframe beginning ([1h - 2h])
d4: shutdown the VM and make the last sync
E: the migration is done and the VM can be started on the new host

option: if the time of d3 sync is longer that 1h (the timefram duration), fail the warm migration and do nothing else

Example with the timeframe too close of the warm migration start:

    fs1          fe1    d1         d2         d3              dX  E     
--+-+--------+----+-----+----------+----------+------.....----+---+------+
20h        21h        22h        23h         0h               22h        23h
                        [ timeframe ]                         [ timeframe ]      

[olivierlambert]

We'll discuss that during our next issue triage run (next week). Adding @marcungeschikts to keep track of it.