I'm no expert but maybe another test might be iperf and watch your cpu utilization while doing it You can set iperf to run between a couple monitors and OSD servers Try setting it at 1500 or your switch's stock MTU then put the servers at 9000 and the switch at 9128 (for packet overhead/management) then run iperf between the servers for both MTU settings then do the same and increase the streams so as to saturate the network iperf will give your network throughput which is usually 90% of the listed Network speed Also by using jumbo frames it will reduce cpu /network cycles as more data is pushed out per ethernet frame for our jumbo frame configuration we saw 26 Gb/s with 1 stream and 37 Gb/s with 10 streams we didn't record it for our stock mtu settings Thanks Joe
>>> Sameer Tiwari <stiw...@salesforce.com> 8/11/2017 11:21 AM >>> Hi, We ran a test with 1500 MTU and 9000MTU on a small ceph test cluster (3mon + 10 hosts with 2 SSD each, one for journal and one for data) and found minimal ~10% perf improvements. We tested with FIO for 4K, 8K and 64K block sizes, using RBD directly. Anyone else have any experience with this? Thanks, Sameer
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