Hey, My current thinking is that it would be great to get the following working for luminous (roughly in order of priority): 1/ add a mon setting for the oldest client version we want to support. this would replace the various mon_allow_* settings that control whenter we user primary-affinity, osd upmap, and gate the crush tunables changes (i.e. you can't set jewel untables if the oldest compat client is firefly). 2/ make sure the above gates the new crush weight sets. 3/ make crushwrapper encode a "legacy" crushmap if (1) we're using weight sets, (2) the client is lacking features for the weight set, but (3) the weight set has a single position and no id remapping. Since these maps are *only* used by clients (not humans), then i don't think there's any need to preserve the original crush weights in a shadow hierarchy; we can just swpa them for the real weights and the legacy clients wll behave as expected. a helper can tell us whether this is possible so that we gate any commands that inject crush map on the compat option in #1. 4/ I would *love love love* it if we could have a mgr task that optimizes the crush weights in a way that Just Works. If we remove any need for the admin to worry about reweighting in luminous I would call it a bit usability win. I think depends on your ongonig investigation in which optimization methods work, and then eventually some mgr work so that it is done automatically. I can work on #1; #2 is something we need to sort before luminous releases to make sure users to shoot themselves in the foot. #3 would be awesome (it will still allow offline optimization tools and maintain compat with clients) and #4 would be the big win IMO. What do you think? sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
