Image says it all. Doing some testing with HCIBench (VMWare ova) to determine what kinds of performance I can expect before taking this box to a temporary production (subplanting a Nimble Array during a migration). System is running 12U3.1. Was running with dedupe vdev (NVME mirror), Meta VDEV (SATA SSD mirror), and 12x 10TB Z2 array. This is after testing it and ditching the pool and building it fresh without dedupe; suspecting it could be related, but that image is *after* the pool nuke and rebuild (NVMe as Meta VDEV, no dedupe, omit SATA SSD); so thought is that if that was in any way related to dedupe that it would have flushed that out as well at that time.
Only "Services" running, according to the GUI at least is iSCSI and SMART; flushed both and still there. Rebooting it seems to resolve, but concerned that putting this into production I'd see this behavior occur and rebooting won't be an option.