[Pacemaker] Resource capacity limit

[Yan Gao]

Hi Andrew and Lars,
The attachment is the first try to implement "Resource capacity limit"
which is issued by Lars from:
https://fate.novell.com/303384

Description:
We need a mechanism for the PE to take resource weight into account to
prevent nodes from being overloaded.

Resources would require certain minimal values for node attributes
(this is available right now); however, they would also "consume" them,
reducing the value of the node attributes for further resource placement.
(This could be a special flag in the rsc_location rule, for example.)
If a node does not have enough capacity available, it is not considered.
..

User case:
Xen guests have memory requirements; nodes cannot host more guests than
the node has physical memory installed.


Configuration example:

node yingying \
	attributes capacity="100"
primitive dummy0 ocf:heartbeat:Dummy \
	meta weight="90" priority="2"
primitive dummy1 ocf:heartbeat:Dummy \
	meta weight="60" priority="1"
..
property $id="cib-bootstrap-options" \
	limit-capacity="true"
..

Because dummy0 has the higher priority, it'll be running on node "yingying".
While this node only has "10" (100-90) capacity remaining now, so dummy1 cannot
be running on this node. If there's no other node where it can be running on,
dummy1 will be stopped.

If we don't want to enable capacity limit. We could set property
"limit-capacity" to "false", or default it.


What do you think about the way it's implemented? Did I do it right?

I also noticed a likely similar planned feature described in
http://clusterlabs.org/wiki/Planned_Features

"Implement adaptive service placement (based on the RAM, CPU etc.
required by the service and made available by the nodes) "

Indeed, this try only supports single kind of capacity, and it's not
adaptive... Do you already have a thorough consideration about this
feature?
Any comments or suggestions are appreciated. Thanks!

Regards,
  Yan
-- 
ygao at novell.com
Software Engineer
China Server Team, OPS Engineering

Novell, Inc.
Making IT Work As One™



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