I have a Mac Pro (2019) with an internal Pegasus R4i and an external Pegasus3 R4. The external drive is purely used for TimeMachine and the R4i is my primary data and workspace storage. When I bought the MacPro I replaced the stock 3TB Toshiba drives in the R4 with new Seagate Ironwolf 10TB (ST10000VN0008) drives, listed at the top of the compatability chart.
I have used the Pegasus3 R4 with other Macs, prior to using it with this MacPro and never run into the situation I'm currently experiencing. Whenever I log in, or switch users, the drives in the unit kick into high gear and the disk activity light will blink rapidly for 20 to 30 minutes. And this is not a TimeMachine backup running. In fact, I would call the disk activity excessive even when compared to a normal TimeMachine backup.
The information in the Promise Utility doesn't seem to provide any particular insight into what could be causing the but it does let me know "All components are OK." I don't know enough about the Mac OS Activity Monitor to know if there's a way to see what's causing the disk activity commotion or not.
Has anyone else experienced anything similar?