Standalone libcrush: call for participation

[Loic Dachary <loic@dachary.org>]

Hi Ceph,

The idea of packaging CRUSH [1] as a standalone library that can be used by Ceph and other projects is not new. 

From the beginning Sage expected/hoped that the algorithm would be useful for lots of different applications. Other storage systems, load balancers, CDNs, or any other distributed thing where a compact description of how to map a large number of things to other things would be useful.  This has partly been proven out in that some storage systems "use CRUSH," but they use it in the sense that they reimplemented something based on the underlying algorithm.

It's also a place where we haven't seen a need to do anything ceph-specific; the problems we've fixed and changes we've made are general issues with the original algorithm and implementation.  The main barrier has been that the code and tools are built using a lot of the generic ceph infrastructure like encode/decode/bufferlists.

The beginning of the next ceph release cycle seems like a good time to initiate that effort. If someone is willing to help with the bootstrap, now is a good time. The library will be hosted under the libcrush.org domain name. But that's about the only thing that happened so far :-)

Cheers

[1] https://github.com/ceph/ceph/tree/master/src/crush

-- 
Loïc Dachary, Artisan Logiciel Libre