SUCCESS! THANK YOU LACIE! Using the process described by fematheron above it's now back to peak performance. Me: 2022 Mac Studio M1 Max 5Big Thunderbolt 2 20TB RAID 5 WD Red Pro WD4003FFBX drives Cables: OEM Lacie TB2 cable into Apple TB2 to TB3 adaptor Ports: rear TB port on Mac Studio Lacie website specs state performance benchmark for a 5Big 20TB in RAID 5 should be: 720 MB/s Write 700 MB/s Read Black Magic Speed Test 1GB Stress File Initial peak of 701 MB/s Write, (average: 660~ MB/s over 3 mins) Initial peak of 680 MB/s Read, (average: 650~ MB/s over 3 mins) 5GB Stress File: Initial peak of 750 MB/s Write, (average: 540~ MB/s over 3 mins) Initial peak of 710 MB/s Read, (average: 550~ MB/s over 3 mins)

This popped up this morning. (macOS 12.3.1). Potential to disrupt on a future macOS update? Refers to this:    LaCieMvumi:    Version: 1.3.22    Last Modified: 19/10/2021, 11:32 am    Bundle ID: com.lacie.driver.mvumi    Notarized: Yes    Loaded: Yes    Obtained from: Identified Developer    Kind: Universal    Architectures: arm64e, x86_64    64-Bit (Intel): Yes    Location: /Library/Extensions/LaCieMvumi.kext    Kext Version: 1.3.22    Load Address: 18446741874802737000    Loadable: Yes    Dependencies: Deprecated    Signed by: Developer ID Application: Seagate Technologies LLC (57HJ3KH2XC), Developer ID Certification Authority, Apple Root CA

Hi Adam. I am also still experiencing the same issue as you, both my M1 Mac mini or my M1 Max Mac Studio. There's nothing we can do until Lacie fixes the driver. Personally, I am moving away from Lacie. Either to another SAS or switch to NAS and Gigabit ethernet for future proofing. Synology DiskStation DS1821+ or OWC ThunderBay 8