High IO Wait

[thejlowe]

We have a TVS-EC1680U-SAS-RP NAS running on firmware 4.4.1.1216 that is for our Microsoft Failover Cluster environment utilizing iSCSI connections. We also have 4TB of SSD cache in a RAID 10 setup that is currently disabled for troubleshooting purposes.

Our issue is that when I am creating a new Hyper-V disk and look at Resource Monitor > System Resource > CPU, the IO Wait increases to around 70%. If I am also moving any storage in the Failvoer Cluster, the IO Wait increases to around 85%+. When the new Hyper-V disk or Storage move has completed, IO wait goes back down to about 0% immediately.

Is this normal behavior or is there an underlying issue that I'm missing?