Re: Forcing Ceph into mapping all objects to a single PG

[Daniel Hofmann <daniel@trvx.org>]

Follow up: I wrote a small Python script for evaluating the object to
placement mapping's quality. I'm using a Chi-Squared statistical
hypothesis test.

Here is the script and also an example output for a few rados benchmark
writes:

> https://gist.github.com/daniel-j-h/d7d87dfe5de3c5bbfd0f

Maybe you're interested in checking your cluster's mapping quality.

More on the method and the output's meaning:
> https://en.wikipedia.org/wiki/Chi-squared_test
> http://en.wikipedia.org/wiki/P-value

I'm still interested in a cluster-specific mapping as discussed in the
other mailinglist posts.

Cheers,
Daniel