While the drives were not in an S2D pool, I had enabled the following options in devmgmt.msc:
"Enable write caching on the device"
"Turn off Windows write-cache buffer flushing on this device"
After setting these, the drives showed as "IsPowerProtected = True" prior to S2D pool creation. After creating the S2D pool and performing a "Get-PhysicalDisk | Get-StorageAdvancedProperty", they all report false and give an error code of 1 for the caching property.
The S2D pool, however, shows "IsPowerProtected = True".
This is a two node setup with dual 10Gbe adapters running RDMA. RDMA runs at over 1.2Gbps and I have RSS configured for the network adapters. There are two of these caching drivings sitting in front of the capacity storage and both are showing as "Journal". These are write-intensive drives with read-intensive capacity drives.
I was off on my initial throughput statement. I'm receiving the following with dskspd:
diskspd.exe -t10 -o32 -b4k -si -Sh -w100 -d60 -D -L -c5g C:\ClusterStorage\WSR1-HV-01\test.io (roughly 350MB/s write throughput with caching turned off)
Start-FleetSweep -b 4 -t 8 -o 8 -w 100 -d 60 -p si (testing sequential writes, I see it max out at about 450MB/s on a node).
File copies, although not the most accurate, from and NVMe to the S2D cluster, I get between 300MB/s and 400MB/s. Individual disk performance is far higher when not in an S2D cluster or using Starwinds VSAN.
I'm not sure if these numbers are par for the course on a 2 node S2D setup, or if it's still something to do with windows reporting incorrect drive abilities.