Hello Jiri, David [+cc dgilbert] On Thursday 29 August, 2024 at 04:58:39 pm IST, Jiri Denemark <jdenemar@xxxxxxxxxx> wrote: >> - Is there an ideal time to wait before switching to postcopy? > > Not really. As the name suggests this is meant as a timeout, > So logically the timeout should be long enough to give pre-copy > migration time to do its job. > >> * The feature page below suggests to wait until one cycle of RAM migration has completed >> -> https://wiki.qemu.org/Features/PostCopyLiveMigration ; > > Right, that's definitely a good approach as only memory pages that > changed during migration will have to be transferred from the source. Some follow-up questions: * Why is it recommended to complete at least one cycle of RAM migration before switching to Postcopy mode? * What are the risks if we switch to postcopy before completing one cycle of RAM migration? * Is it plausible to start migration in postcopy mode from the beginning? ie. without the first pre-copy pass? * I'm asking because even when we switch to postcopy before completing the first (pre-copy) pass, the migration seems to work fine most of the times. Errors occur occasionally. It does not _always_ fail with errors. - Could we file bugs for this occasional failure? OR that is expected because we did not wait to complete first (pre-copy) round of migration. * I'd appreciate if you could help to clarify this. Thank you. --- -Prasad
