Problems Between macOS Catalina and Promise RAIDs

Posted on by Larry

Tom Wheeler sent me the following note:


I wanted you to know about a problem that I have discovered after installing Mac OS Catalina on my iMac Pro. I have a Promise Pegasus 3 R6 that I have kept fully up to date with both firmware and software updates as they became available from Promise.

Under Mac OS Mojave I had no problems booting into Windows 10 using the Option Key on startup to bring up the Storage Manager and selecting Windows. After installing Catalina, I am unable to boot into Windows 10 via this method. The boot into Windows 10 hangs at the Windows logo and the spinning circle of white dots. If I detach the Pegasus 3 from my iMac, I can use this method to boot into Windows 10 with no problems. Furthermore, I can attach the Pegasus 3 to my iMac Pro after booting into Windows 10 and it works fine in Windows (using Mac Drive)

In Mac OS Catalina I find that the Promise Utility does not operate completely correctly, i.e. failing to save a Subsystem Service Report after clicking on Save, and I find that after rebooting into OS Catalina, the Pegasus 3 runs for about 3-5 minutes each time apparently doing some sort of maintenance operation. However, in Catalina I am able to use the Pegasus 3 without any problems. I have contacted Promise Support and they acknowledge that the Pegasus 3 is not supported in Catalina and no time frame for issuing new firmware that will enable the Pegasus systems to work with Catalina is known.

Since many individuals on Macs use the Promise Pegasus raid 5 systems for editing, I thought you might wish to caution your readers about updating to Catalina until Promise issues new firmware and software that will support the Pegasus systems in Catalina.

Thank you.

Tom Wheeler

Larry adds: Tom, thanks for letting us know. This is another example reinforcing caution when upgrading.

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12 Responses to Problems Between macOS Catalina and Promise RAIDs

  1. SAUTIER says:

    Hi Larry, I’m on the same situation. I have a Promise Pegasus 1 R1 and a Promise pegasus 2 R6 … A new Promise utility came out the 21/11 … Promise explain to me that : “I would suggest to use Mojave for Pegasus 2 as it is stable. The catalina is compatible but it’s not stable and we have been receiving some issues about it. So now it’s not a good time to upgrade.”

    You can download this driver here :

    Can you tell me if it solve your problem ?? For a photographer user , is Catalina 10.15.1 and the 10.15.2 who is arriving next week is stable ???

    Best regards

  2. SAUTIER says:

    Here the link driver and firmware you have to upgrade.

  3. Tom Wheeler says:


    I wanted to provide a final update on the issues with Promise Pegasus 3 systems operating improperly under Bootcamp after the installation of Mac OS Catalina.
    (When one attempts to boot into Windows 10 under Bootcamp after installing OS Catalina, the boot hangs at the Microsoft spinning logo of white spots.)

    I have been in almost constant contact with Promise Support since October 8, 2019 when this issue arose. After months of requesting information (which I supplied) Promise Support informed me today that the issue is with Bootcamp and not with the Promise Pegasus, that they do not support Bootcamp, and that they can do nothing to resolve the issue. This exact same issue arose with my Promise Pegasus 3 just after buying a new iMac Pro when they came out. Eventually promise sent me a firmware upgrade that resolved the problem. Although Promise issued a firmware upgrade to the Pegasus 3 in November 2019, it does not resolve this problem. Promise has not updated the drive for the Pegasus 3 since May 2017.

    If anyone is planning to use a Pegasus 3 system under Bootcamp, then they should be aware that it will not allow you to boot into Windows 10 under Mac OS Catalina and that Promise has washed their hands of the problem.

    • Larry says:


      Thanks for the update. This information is important to know BEFORE you buy gear.

      For those considering purchasing RAIDs for similar work, please check with the vendor’s support staff before buying.


  4. Hello,
    I have Peagus R 4. I am facing a problem, in my hard disk, upper led blinks red, and down led blinks blue, all the four hard drives.I cannot read data in my Mac. I am based in Mumbai, India. Please help

    • Larry says:


      You are sadly correct. There’s a problem with Promise RAIDs and Catalina. You’ll need to contact Promise Technical Support to get this resolved.


  5. cannot mount pegasus R4 on mac book pro 2013 model, catalina software

    • Larry says:


      Sadly, you are correct. This is a problem with Promise RAIDS, as this article discusses. You’ll need to contact Promise Technology for a fix.


  6. Hello everyone.

    I just got a MBP16″ with Catalina 10.5.3 MacOS X installed.

    I have a Promise J4 and I try Promise Utility 37 and 39 and none of both works. Does not even show the diveces.

    I have it using a Thunderbolt 3 to Thunderbolt 2 Adaptor. In System Report I can see it is there and actually recognize other Thunderbolt Units but no the Promise J4 with 4x HDDs 2.5″ Drives.

    Please provide with a solution ASAP.

    Thank you.

    • Larry says:


      The only people that can solve this is the tech support folks at Promise. You’ll need to contact them directly, as this requires a firmware upgrade.


  7. Phemelo Phiri says:

    Hi Larry. I have a Paragus R6 and shortly after upgrading my OS to Catalina, the raid started to be slow and it got to a point where it crashes premiere and now I can’t copy files from the raid without it crashing. Is this a compatibility issue or something else? Also the raid capacity is 8TB and it’s currently running on 1.68 TB.

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