Hi everyone, The solution is finally here ! I've been calling Lacie for a while explaining the problem of slowness with my Lacie 6big and the apple M1. They told me it was a problem of compatibility and driver and they were trying to fix it. Yesterday they call me back to tell me that they fixed the problem : You have to download the last version of the lacie raid manager : 2.9.3.225 and active the permisions on your mac when you install the software. Now I've got around 800Mb/s write and read in thunderbolt 3 and raid 5. Hope this will help you!

Hi, Same problem here, I have a new apple M1 max and my Lacie 6big 60to in Raid 5 is really slow. 45 mb/s in write speed and 350 mb/s for the read speed with thunderbolt 3 of course. I've tried with usb cable instead of thunderbolt but still the same. Before I had an Imac without apple silicon and my 6 big was working as expected. I can see by this forum that this problem have been here for more than a year now. It's crazy that lacie didn't manage to find a solution for their product to work correctly with apple silicon.