I think the balance_snap_reads and balance_parent_reads would be safety since snap would not be changed, right? Is that any issue with the options rbd_balance_snap_reads and rbd_balance_parent_reads, which is default setting to false now? Regards Ning Yao Gregory Farnum <gfarnum@xxxxxxxxxx> 于2018年12月6日周四 上午11:42写道： > > On Sun, Dec 2, 2018 at 7:37 PM 韦皓诚 <whc0000001@xxxxxxxxx> wrote: > > > > Hi~ > > I want to turn on the "CEPH_OSD_FALG_BALANCE_READS" flag to > > optimize read performance. Do I just need to set flag in librados API > > and is there any other problems? > > While there may be limited cases where it can be useful, there are a > lot of caveats and surprising holes where this doesn't work right or > can cause issues. (Because it reads from replicas — which don't have > the full PG state a primary does — there are numerous situations where > you can retrieve stale or incorrect data.) I would strongly advise > against using it. > -Greg
