Here's what I learned about PG maps from my investigation of the code. First, they don't seem to be involved in deciding what needs reconstruction when a dead OSD is revived. There is a version number stored with the PGs that is probably used for that. It looks like nothing but statistics - the ones you see in a 'ceph status' (or more specifically, 'ceph pg stat' report - and I don't think those statistics affect any automatic operation. The PG map gets updated (version incremented) mainly when an OSD sends those statistics to the monitor cluster. Each OSD sends a statistics report every 6 seconds (default - it's the osd_heartbeat_interval configuration variable) to a monitor. If those statistics differ at all from the previous report, the monitor generates a new PG map. Because the stats include I/O rates, they do tend to be different every time. But there is a limit of one update per second (default - it's the 'paxos_propose_interval' configuration variable) on updates to any of the maps in the monitor database, so on any normal size system, you'll see updates once a second. -- Bryan Henderson San Jose, California _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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