On Fri, May 20, 2011 at 3:05 AM, Henry C Chang <henry.cy.chang@xxxxxxxxx> wrote: > Hi all, > > In my ceph cluster, I saw a pg membership change as below: > > At osdmap epch 160, pg 1.184 was mapped to [4, 6]. > > osdmaptool: osdmap file '160' > parsed '1.184' -> 1.184 > 1.184 raw [4,6] up [4,6] acting [4,6] > > At osdmap epoch 161, however, pg 1.184 was mapped to [0, 5]. > > osdmaptool: osdmap file '161' > parsed '1.184' -> 1.184 > 1.184 raw [0,5] up [0,5] acting [0,5] > > The osdmap are attached. > Is it normal that the pg membership changes like this? I thought at > least one member will stay in the pg in this case? What caused the osd map to change? And did the mapping stay that way, or did it get overridden in one of the subsequent map updates? In general we'd expect the mappings to maintain membership, but I don't think it's a guarantee. What you will see, though, are manual overrides of the CRUSH mapping to a different acting set in subsequent updates, as the new OSDs in the PG start peering and realize that an old OSD would be better-suited for the job (since it has data and none of them do). -Greg -- 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
