Open Stack

On Fri, Jun 29 2012, Doug Hellmann wrote:

> We do have counters for RAM and CPU separate from instance. But the rate at
> which the provider bills for those things may vary based on metadata. My
> example may be bad because it uses 2 values we're measuring, one of which
> also shows up in the metadata for another. As a different example, take the
> instance display name. The display name is under the control of the user
> and is extremely unlikely to reflect a change in the billing rate. However,
> changing the display name changes the metadata for the instance. A naive
> implementation of the processing loop would pick that up and generate
> multiple documents even though there is no need to do so.

Yep, but the display name is not a counter. Memory is a counter. An
instance is made of several counter. We need to split metered objects
based on their "absolute" counter changing (memory, number of core…),
not based on random metadata, i.e. a resource have several meters.

So what was considered as metadata (like memory) so far should changed
to become a meter of an resource (like an instance) and have for this
one a special type (not sure about the type name to use).

We may need to refine our model to be a bit more hierarhical like:

resource --> counter #1 of type 'relative'
      |  `-> counter #2 of type 'absolute'
      `----> counter #3 of type 'if-i-change-you-need-to-split-the-resource-in-several-stuff'

     etc…

-- 
           Julien
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