Hi Anthony and others,
thank you for your reply. To be honest, I'm not even looking for a
solution, i just wanted to ask if latency affects the performance at all
in my case and how others handle this ;)
One of our partners delivered a solution with a latency-optimized
profile for tuned-daemon. Now the latency is much better:
apt install tuned
tuned-adm profile network-latency
# ping 10.1.4.13
PING 10.1.4.13 (10.1.4.13) 56(84) bytes of data.
64 bytes from 10.1.4.13: icmp_seq=1 ttl=64 time=0.047 ms
64 bytes from 10.1.4.13: icmp_seq=2 ttl=64 time=0.028 ms
64 bytes from 10.1.4.13: icmp_seq=3 ttl=64 time=0.025 ms
64 bytes from 10.1.4.13: icmp_seq=4 ttl=64 time=0.020 ms
64 bytes from 10.1.4.13: icmp_seq=5 ttl=64 time=0.023 ms
64 bytes from 10.1.4.13: icmp_seq=6 ttl=64 time=0.026 ms
64 bytes from 10.1.4.13: icmp_seq=7 ttl=64 time=0.024 ms
64 bytes from 10.1.4.13: icmp_seq=8 ttl=64 time=0.023 ms
64 bytes from 10.1.4.13: icmp_seq=9 ttl=64 time=0.033 ms
64 bytes from 10.1.4.13: icmp_seq=10 ttl=64 time=0.021 ms
^C
--- 10.1.4.13 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9001ms
rtt min/avg/max/mdev = 0.020/0.027/0.047/0.007 ms
Am 21.05.24 um 15:08 schrieb Anthony D'Atri:
Check the netmask on your interfaces, is it possible that you're sending inter-node traffic up and back down needlessly?
On May 21, 2024, at 06:02, Stefan Bauer <sb@xxxxxxx> wrote:
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
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--
Mit freundlichen Grüßen
Stefan Bauer
Schulstraße 5
83308 Trostberg
0179-1194767
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