I've been wrestling with IO performance in my cluster and one area I have not yet explored thoroughly is whether or not performance constraints on mon hosts would be likely to have any impact on OSDs. My mons are quite small, and one in particular has rather high IO waits (frequently 30% or more) due to the other work it performs, notably hosting postgres for Openstack which is quite chatty for some reason. Is this likely to trickle-down into the OSDs performance? Everything I've seen online indicates the performance between MONs and OSDs should be decoupled, but I'd like to hear some real world experiences.
Thanks!
QH
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