G-Speed Studio XL now working with my 2021 MacBook Pro M1 Pro Monterey

There are a few postings on this forum about G-Speed Studios not working (i.e., won’t show up in Finder) on 2021 MacBook Pro M1s running Monterey. I had that issue with my devices.

I found a workaround and I am now able to access my G-Speed Studio XL 24TB on my 2021 MacBook Pro M1 Pro running Monterey.

Basically, you have to:

(1) download the Promise Pegasus2 driver (R_MacDrv_V6_2_16)


(2) Change the security settings on the 2021 MacBook Pro startup disk to Reduced Security, “Allow user management of kernel extensions from identified developers”

After performing both of these steps, which included a reboot or two, I plugged the TB2 cable from my G-Speed Studio XL into the TB2/TB3 adapter dongle and plugged that into my 2021 MacBook Pro. In about 30 seconds (maybe less), the G-Speed Studio XL appeared in Finder and I was able to access all the files. Note: I did find the Blackmagic Disk Speed to be slower (but still workable, in my case).

Links provided to respective files and documentation below:

Note: For the Promise Pegasus2 driver (after accessing the link/page), scroll down to the “Compatibility” section and under Models, download the Pegasus2 Series driver. Install the downloaded package on your 2021 MacBook Pro.

macOS Big Sur Support - Promise Pegasus Compatibility List

Change security settings on the startup disk of a Mac with Apple silicon

I have tried this with no success. That was essentially the same steps I took to get the SSD Shuttles to work with the M1 iMac when it came out, but no luck with any of my machines (M1 13 MBP, M1 mini, M1 iMac, M1 16 MBP) all running Monterey.

Welshofer, really sorry to hear this isn’t working for you - it is very frustrating.

Maybe we can compare our system settings and possibly see a difference which might point out a fix for you?

Happy to give it a try, if you’d like.

For example, when I review my System Report, Controller, I see:

Boot Policy:
Secure Boot: Reduced Security
System Integrity Protection: Enabled
Signed System Volume: Enabled


I’m not thinking these are the only parameters to check. Just thinking out loud on parameters to compare, possibly.

In any case, best of luck to you - I do hope you get this resolved quickly/soon.