[ClusterLabs] manner in which cluster migrates VirtualDomain - ?

[Ken Gaillot]

On Tue, 2023-04-18 at 14:58 +0200, lejeczek via Users wrote:
> Hi guys.
> 
> When it's done by the cluster itself, eg. a node goes 'standby' - how
> do clusters migrate VirtualDomain resources?

1. Call resource agent migrate_to action on original node
2. Call resource agent migrate_from action on new node
3. Call resource agent stop action on original node

> Do users have any control over it and if so then how?

The allow-migrate resource meta-attribute (true/false)

> I'd imagine there must be some docs - I failed to find

It's sort of scattered throughout Pacemaker Explained -- the main one
is:

https://clusterlabs.org/pacemaker/doc/2.1/Pacemaker_Explained/html/advanced-options.html#migrating-resources

> Especially in large deployments one obvious question would be - I'm
> guessing as my setup is rather SOHO - can VMs migrate in sequence or
> it is(always?) a kind of 'swarm' migration?

The migration-limit cluster property specifies how many live migrations
may be initiated at once (the default of -1 means unlimited).
-- 
Ken Gaillot <kgaillot at redhat.com>