On Mon, 23 Feb 2015, Somnath Roy wrote: > Hi, > Can anyone help me understand what will happen in the following scenarios ? > > 1. Current PG map : 3.5 -> OSD[1,2,3] > > 2. 1 is down and new map : 3.5 -> OSD[2,3,4] More likely it's: 1: 3.5 -> [1,2,3] 2: 3.5 -> [2,3] (osd.1 is down) 3: 3.5 -> [2,3,4] (osd.1 is marked out) > 3. Need to for backfill recovery for 4 and it started If log recovery will work, we'll do that and it's nice and quick. If backfill is needed, we will do 4: 3.5 -> [2,3] (up=[2,3,4]) (pg_temp record added to map to log-recoverable OSDs) > 4. Meanwhile OSD 1 came up , it was down for short amount of time 5: 3.5 -> [1,2,3] (osd.1 is back up and in) > 5. Will pg 3.5 mapping change considering OSD 1 recovery could be log > based ? It will change immediately when osd.1 is back up, regardless of what data is where. If it's log recoverable, then no mapping changes will be needed. If it's not, then 6: 3.5 -> [2,3,4] (up=[1,2,3]) (add pg_temp mapping while we backfill osd.1) 7: 3.5 -> [1,2,3] (pg_temp entry removed when backfill completes) > 6. Also, if OSD 4 recovery could be log based, will there be any change > in pg map if OSD 1 is up during the recovery ? See above Hope that helps! 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
