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
Sage Weil wrote:
> On Fri, 25 Jul 2014, Daniel Hofmann wrote:
>> The main issue however is not the hash's strength, but the fact that
>> once pre-computed, I'm able to use preimages on **every Ceph cluster out
>> there**. (As the hash functions's output is a deterministic function of
>> the object
On Fri, 25 Jul 2014, Daniel Hofmann wrote:
> The main issue however is not the hash's strength, but the fact that
> once pre-computed, I'm able to use preimages on **every Ceph cluster out
> there**. (As the hash functions's output is a deterministic function of
> the object's name only)
>
> I agr
The main issue however is not the hash's strength, but the fact that
once pre-computed, I'm able to use preimages on **every Ceph cluster out
there**. (As the hash functions's output is a deterministic function of
the object's name only)
I agree in that the general issue is inherent in hash-placem
Gah, typed "fletcher4" when I meant "rjenkins" - still, the same applies.
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Gregory Farnum wrote:
> On Mon, Jul 21, 2014 at 3:27 PM, Daniel Hofmann wrote:
>> Preamble: you might want to read the decent formatted version of this
>> mail at:
>>> https://gist.github.com/daniel-j-h/2daae2237bb21596c97d
>> ---
>>
>> Ceph's object mapping depends on the rjenkins hash func
On Mon, Jul 21, 2014 at 3:27 PM, Daniel Hofmann wrote:
> Preamble: you might want to read the decent formatted version of this
> mail at:
>> https://gist.github.com/daniel-j-h/2daae2237bb21596c97d
>
>
> Motivation
> --
>
> Recently I was wondering how Ceph (i.e. Rados in particular) maps o
Preamble: you might want to read the decent formatted version of this
mail at:
> https://gist.github.com/daniel-j-h/2daae2237bb21596c97d
Motivation
--
Recently I was wondering how Ceph (i.e. Rados in particular) maps object
to Placement Groups (PGs).
It basically works like the followin
