RE: [tosca] tosca.nodes.Compute offering questions

Hi Luca,

You’re asking good questions. Tosca provides a mechanism to specify the CPU, memory, disk, OS, etc. requirements for various components. It does not specify how the orchestrator is supposed to fulfill these requirements. You can decide to pick any compute node that has at least the memory, CPU, and disk requested. If you decide to return excess resources, that decision is entirely up to you.

There have been discussions about addition additional semantics to “requirements” specification (e.g. best effort semantics where you try to get as close as you can to the desired CPU, memory, and disk requirements) but these have not yet been added to the spec.

Chris Lauwers

Ubicity Corp.

From: tosca@lists.oasis-open.org [mailto:tosca@lists.oasis-open.org] On Behalf Of Luca Gioppo
Sent: Thursday, June 04, 2015 3:12 AM
To: TOSCA
Subject: [tosca] tosca.nodes.Compute offering questions

Some questions on the Compute node definition.

From a model point of view the definition is logical, from the Cloud API available is less usefull.

On CloudStack for example I create a new virtual machine by sending the templateId the offeringId and the zoneId.

To get those information my orchestrator has to match the generic request of CPU, Memory, disk, operating system etc with the existing offerings.

Is this the way that the standard has to be used?

So to create a compute resource the orchestrator must "guess" the correct combination?

Is there a good practice to adopt for giving back results or is a free decision of the orchestrator implementor?

I could find a combination of offering that match the node description or not in case not I should return error to end user or try to go to the nearest good offering?

Maybe this problem could araise the need of some new attribute in the standard for forcing a proper behaviour?

Thanks

Luca

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