[pve-devel] Default cache mode for VM hard drives

[Dietmar Maurer]

> > > AFAIK kvm live migration issues a disk flush, so that should not be a problem?
> > >
> > > Out if sync blogs do not appear during migration, they appear under normal
> work
> > > load.
> >
> > I do not really understand that. What do you mean by "Out if sync blogs do not
> appear during migration"?
> Out of sync blocks are blocks that contain different data on two nodes. Such
> blocks appear when a VM just work under normal load and usually it happens for
> the area where VM's swap is placed. The longer VM is online, the more out of
> sync blocks appear. If we try to migrate such a VM online it will crash because
> data in VM's swap will be different after migration.

Again, migration code flush all changes to disk, so there are no "out of sync" blocks
after migration. What do I miss?