On Mon, Nov 7, 2011 at 1:03 PM, Leander Yu <[email protected]> wrote: > Hi Greg, > Will there be any performance impact if there are too many mons?
Eventually there could be a small one. Every time the monitor systems do a map update (to, for instance, change the record of whether an OSD is up or down, or which MDS owns what data) it needs to get agreement from a strict majority of the monitors. The more monitors you have the higher the variance in latency you can get for this operation, and the more bandwidth the leader monitor needs to devote to sending out the updates to all the other monitors. But under normal operation these map updates are "rare" (maybe one every 5 seconds) and they're never in the client's critical path for data transfer, so any performance issues would be noticed based on the side effects they produce, not by client performance. -Greg -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
