[ClusterLabs] Antw: Re: Set a node attribute for multiple nodes with one command

[Ulrich Windl]

>>> Ken Gaillot <kgaillot at redhat.com> schrieb am 18.11.2016 um 16:17 in Nachricht
<d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com>:
> On 11/18/2016 08:55 AM, Kostiantyn Ponomarenko wrote:
>> Hi folks,
>> 
>> Is there a way to set a node attribute to the "status" section for few
>> nodes at the same time?
>> 
>> In my case there is a node attribute which allows some resources to
>> start in the cluster if it is set.
>> If I set this node attribute for say two nodes in a way - one and then
>> another, than these resources are not distributed equally between these
>> two nodes. That because Pacemaker picks the first node to with this
>> attribute is set and immediately starts all allowed resources on it. And
>> this is not the behavior i would like to get.
>> 
>> Thank you,
>> Kostia
> 
> Not that I know of, but it would be a good feature to add to
> attrd_updater and/or crm_attribute.

With crm (shell) you don't have transactions for node attributes, but for the configuration. So if you add a location restriction preventing any resources on your nodes, then enable the nodes, and then delete the location restrictions in one transaction, you might get what you want. It's not elegant, but itt ill do.

To the crm shell maintainer: Is is difficult to build transactions to node status changes? The problem I see is this: For configuration you always have transactions (requiring "commit), but for nodes you traditionally have non (effects are immediate). So you'd need a thing like "start transaction" which requires a "commit" or some kind of abort later.

I also don't know whether a "shadow CIB" would help for the original problem.

Ulrich

> 
> You can probably hack it with a dampening value of a few seconds. If
> your rule checks for a particular value of the attribute, set all the
> nodes to a different value first, which will write that value and start
> the dampening timer. Then set all the attributes to the desired value,
> and they will get written out together when the timer expires.
> 
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