Ceph » RADOS

I think the thing to do here is extend the CrushWrapper interface (probably by wrapping something in mapper.c or builder.c) with functions to reweight a specific item in the tree, and then recalculate the ancestor weights accordinging. This is imperfect, as a given item can appear multiple times in the hierarchy, and maps deliberately allow parent weights to diverge from the sum of their children, but those situations don't come up for most users or use cases.

Then some monitor commands to actually do it.. 'osd crush reweight osd1 .5' or something along those lines. Maybe even one that spits out osd weights.