On Mon, 13 Feb 2017, Gregory Farnum wrote: > On Mon, Feb 13, 2017 at 1:15 PM, Sage Weil <sweil@xxxxxxxxxx> wrote: > > On Mon, 13 Feb 2017, Loic Dachary wrote: > >> I get the expected behavior for replica 1 (which is what > >> CRUSH.straw2_reweight does). The movement between buckets observered > >> below is for replica 2. > > > > Oh, right, now I remember. The movement for the second replica is > > unavoidable (as far as I can see). For the second replica, sometimes we > > end up picking a dup (the same thing we got for the first > > replica) and trying again; any change in the behavior of the first choice > > may mean that we have more or less "second tries." Although any given try > > will behave as we like (only moving to or from the reweighted item), > > adding new tries will pick uniformly. In your example below, I think all > > of the second replicas that moved to osds 0-9 were objects that originally > > picked a dup for the second try and, once 10 was added, did not--because > > the first replica was now on the new osd 10. > > Just to be clear, that's within a bucket, right? Right, within a (straw2) bucket. > Because obviously changing bucket weights in the CRUSH hierarchy will > move new data to them, not all of which ends up on the new disk. Yep! 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
