Hi Ceph,

There is a need for a cluster to share code such as cls 
https://github.com/ceph/ceph/tree/master/src/cls or erasure code plugins 
https://github.com/ceph/ceph/tree/master/src/erasure-code/.

These plugins could have a life cycle independent of Ceph, as long as they 
comply to the supported API ( 
https://github.com/ceph/ceph/blob/master/src/erasure-code/ErasureCodeInterface.h
 ). For erasure code plugins it currently works this way (or it will as soon as 
https://github.com/ceph/ceph/pull/2397 is merged):

a) upgrade from Hammer to I* half the OSD nodes. The new I* have new erasure 
code plugins
b) the MON will refuse to create an erasure coded pool using the new I* 
plugins, otherwise the Hammer nodes will find themselves unable to participate 
in the pool

Instead it could work this way:

a) upgrade from Hammer to I* half the OSD nodes. The new I* have new erasure 
code plugins
b) the new erasure code plugins are uploaded to a "plugins" pool
c) an erasure coded pool is created using a new plugin from I*
d) the Hammer OSD downloads the plugin from the pool and can participate in the 
pool

It is easier said than done and there are a lot of details to consider. However 
it not different from maintaining an Operating System that includes shared 
libraries and the path to do so properly is well known.

Thoughts ?

Cheers

-- 
Loïc Dachary, Artisan Logiciel Libre

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