On 19/10/17 11:00, Dennis Benndorf wrote: > Hello @all, > > givin the following config: > > * ceph.conf: > > ... > mon osd down out subtree limit = host > osd_pool_default_size = 3 > osd_pool_default_min_size = 2 > ... > > * each OSD has its journal on a 30GB partition on a PCIe-Flash-Card > * 3 hosts > > What would happen if one host goes down? I mean is there a limit of downtime > of this host/osds? How is Ceph detecting the differences between OSDs within > a placement group? Is there a binary log(which could run out of space) in the > journal/monitor or will it just copy all object within that pgs which had > unavailable osds? > > Thanks in advance, > Dennis
When the OSDs that were offline come back up, the PGs on those OSDs will resynchronise with the other replicas. Where there are new objects (or newer objects in the case of modifications), the new data will be copied from the other OSDs that remained active. There is no binary logging replication mechanism as you might be used to from mysql or similar. Rich
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