I'm setting up a new 2-node (+ witness appliance on a 3th, lower performance host, 1Gbit NIC) stretched cluster. All are ESXi 6.7 Update 1, same for Witness and vCenter appliance.
Both hosts are identical, SuperMicro's with 256GB RAM, 8x1TB SSD (7 capacity + 1 cache diskgroup). Both have a 30Gbit NIC's and a 10Gbit fiber interconnect, with a distance of ~100km in between. The roundtrip latency of this interconnect is around 5ms (I know, this is the limit).
Most health checks are green, except a strange one, considering both machine and software configs are identical:
I don't understand why the 10.0.0.110 gets a warning, while the 10.0.0.112 is green. Both versions are identical.
And the recommended drivers are different...
This is another warning, but related to the one before. Same strange thing. Both installed drivers on the hosts are identical, same for the hardware (SAS controllers).
So, my question. I'm experiencing write performance issues. I have a write performance of 65MB/s to the vSan datastore (e.g. restoring a backup), and a read performance of 550MB/s, wich is good.
Is the low write performance because of the long distance between the two sites? Or because of the FW/dirver warnings of the controller? But, when both hosts weren't a part of the stretched cluster, they had a good write performance.
What is the best practice in this setup to fix the controller warnings? Can I update both hosts individual, or does this needs to be done via the cluster (I'm fairly new to this, but the update procedure for hosts which are part of a cluster is quite confusing for me)?
In case the network distance is causing the low write performance, would jumbo frames (MTU 9000) help? Or any other thing I could do?
However, when I deploy 10 test VM's, and do write performance tests in those VM's, I get a backend throughput of ~500MB/s in the vSan. Why is this reaching 500MB/s, while using 10VM's, while I can't get anything higher than 65MB/s on one VM, or a direct write when doing a restore directly to the vSan datastore?
Thanks for your help!