Dear Users, i recently setup a new ceph 3 node cluster. Network is meshed between all nodes (2 x 25G with DAC). Storage is flash only (Kioxia 3.2 TBBiCS FLASH 3D TLC, KCMYXVUG3T20) The latency with ping tests between the nodes shows: # ping 10.1.3.13 PING 10.1.3.13 (10.1.3.13) 56(84) bytes of data. 64 bytes from 10.1.3.13: icmp_seq=1 ttl=64 time=0.145 ms 64 bytes from 10.1.3.13: icmp_seq=2 ttl=64 time=0.180 ms 64 bytes from 10.1.3.13: icmp_seq=3 ttl=64 time=0.180 ms 64 bytes from 10.1.3.13: icmp_seq=4 ttl=64 time=0.115 ms 64 bytes from 10.1.3.13: icmp_seq=5 ttl=64 time=0.110 ms 64 bytes from 10.1.3.13: icmp_seq=6 ttl=64 time=0.120 ms 64 bytes from 10.1.3.13: icmp_seq=7 ttl=64 time=0.124 ms 64 bytes from 10.1.3.13: icmp_seq=8 ttl=64 time=0.140 ms 64 bytes from 10.1.3.13: icmp_seq=9 ttl=64 time=0.127 ms 64 bytes from 10.1.3.13: icmp_seq=10 ttl=64 time=0.143 ms 64 bytes from 10.1.3.13: icmp_seq=11 ttl=64 time=0.129 ms --- 10.1.3.13 ping statistics --- 11 packets transmitted, 11 received, 0% packet loss, time 10242ms rtt min/avg/max/mdev = 0.110/0.137/0.180/0.022 ms On another cluster i have much better values, with 10G SFP+ and fibre-cables: 64 bytes from large-ipv6-ip: icmp_seq=42 ttl=64 time=0.081 ms 64 bytes from large-ipv6-ip: icmp_seq=43 ttl=64 time=0.078 ms 64 bytes from large-ipv6-ip: icmp_seq=44 ttl=64 time=0.084 ms 64 bytes from large-ipv6-ip: icmp_seq=45 ttl=64 time=0.075 ms 64 bytes from large-ipv6-ip: icmp_seq=46 ttl=64 time=0.071 ms 64 bytes from large-ipv6-ip: icmp_seq=47 ttl=64 time=0.081 ms 64 bytes from large-ipv6-ip: icmp_seq=48 ttl=64 time=0.074 ms 64 bytes from large-ipv6-ip: icmp_seq=49 ttl=64 time=0.085 ms 64 bytes from large-ipv6-ip: icmp_seq=50 ttl=64 time=0.077 ms 64 bytes from large-ipv6-ip: icmp_seq=51 ttl=64 time=0.080 ms 64 bytes from large-ipv6-ip: icmp_seq=52 ttl=64 time=0.084 ms 64 bytes from large-ipv6-ip: icmp_seq=53 ttl=64 time=0.084 ms ^C --- long-ipv6-ip ping statistics --- 53 packets transmitted, 53 received, 0% packet loss, time 53260ms rtt min/avg/max/mdev = 0.071/0.082/0.111/0.006 ms If i want best performance, does the latency difference matter at all? Should i change DAC to SFP-transceivers wwith fibre-cables to improve overall ceph performance or is this nitpicking? Thanks a lot. Stefan