[ClusterLabs] manner in which cluster migrates VirtualDomain - ?

lejeczek peljasz at yahoo.co.uk
Wed Apr 19 02:00:34 EDT 2023

On 18/04/2023 21:02, Ken Gaillot wrote:
> On Tue, 2023-04-18 at 19:36 +0200, lejeczek via Users wrote:
>> On 18/04/2023 18:22, Ken Gaillot wrote:
>>> 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).
>> But if this is cluster property - unless I got it wrong,
>> hopefully - then this govern any/all resources.
>> If so, can such a limit be rounded down to RA type or
>> perhaps group of resources?
>> many thanks, L.
> No, it's global
To me it feels so intuitive, so natural & obvious that I 
will ask - nobody yet suggested that such feature be 
available to smaller divisions of cluster independently of 
global rule?
In the vastness of resource types many are polar opposites 
and to treat them all the same?
Would be great to have some way to tell cluster to run 
different migration/relocation limits on for eg. 
compute-heavy resources VS light-weight ones - where to 
"file" such a enhancement suggestion, Bugzilla?

many thanks, L.

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