[openstack-dev] [OpenStack-dev][Cinder] Driver stats return value: infinite or unavailable

John Griffith john.griffith8 at gmail.com
Thu Dec 18 18:09:20 UTC 2014

On Thu, Dec 18, 2014 at 1:56 AM, Eduard Matei
<eduard.matei at cloudfounders.com> wrote:
> Hi everyone,
> We're in a bit of a predicament regarding review:
> https://review.openstack.org/#/c/130733/
> Two days ago it got a -1 from John G asking to change infinite to
> unavailable although the docs clearly say that "If the driver is unable to
> provide a value for free_capacity_gb or total_capacity_gb, keywords can be
> provided instead. Please use ‘unknown’ if the array cannot report the value
> or ‘infinite’ if the array has no upper limit."
> (http://docs.openstack.org/developer/cinder/devref/drivers.html)
> After i changed it, came Walter A. Boring IV and gave another -1 saying we
> should return infinite.
> Since we use S3 as a backend and it has no upper limit (technically there is
> a limit but for the purposes of our driver there's no limit as the backend
> is "elastic") we could return infinite.
> Anyway, the problem is that now we missed the K-1 merge window although the
> driver passed all tests (including cert tests).
> So please can someone decide which is the correct value so we can use that
> and get the patched approved (unless there are other issues).
> Thanks,
> Eduard
> --
> Eduard Biceri Matei, Senior Software Developer
> www.cloudfounders.com
>  | eduard.matei at cloudfounders.com
> CloudFounders, The Private Cloud Software Company
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Hi Eduard,

First, I owe you an apology; I stated "unavailable" in the review, but
should've stated "unknown".  We're in the process of trying to
eliminate the reporting of infinite as it screwed up the weighing

Note that Zhiteng adjusted the scheduler so this isn't such a big deal
anymore by down-grading the handling of infinite and unknown [1].

Anyway, my suggestion to not use infinite is because in the coming
weeks I'd like to remove infinite from the stats reporting altogether,
and for those backends that for whatever reason don't know how much
capacity they have use a more accurate report of "unknown".

Sorry for the confusion, I think the comments on your review have been
updated to reflect this, if not I'll do that next.


[1]: https://github.com/openstack/cinder/commit/ee9d30a73a74a2e1905eacc561c1b5188b62ca75

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