Hi Sage, On 05/03/2017 05:09 PM, Sage Weil wrote: > 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. Good idea ! I created http://tracker.ceph.com/issues/19836 and will work on that. > 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? If the optimization algorithm proposed in "revisiting uneven CRUSH distributions" actually works, it seems possible to have something automated and transparent to the user. I doubt this can happen before Luminous though. Cheers -- Loïc Dachary, Artisan Logiciel Libre -- 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
