Pegasus2 R4 orange power light and not mounting

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Richerd Reynolds posted this 04 February 2026

Hi all, I have the Pegasus2 R4 with 4x4TB HDD connected to a MacPro late 2013. My unit was having issues where it would randomly unmount and remount causing multiple "Your disk was not ejected properly" messages. Then several days ago the volume unmounted, the power button light turned orange, and could not be shut down via the, now, orange button. The thunderbolt light is lit and blue, the fan is spinning, all of the drives are showing blue and spinning up when powered/plugged in. Also, on occasion, it causes a kernel panic. The system report shows that it was caused by com.promise.driver.stex. There is no window in the Promise Utility app and all the menu items are greyed out.  

Here's what I've tried so far:

  • Unplugged the unit, waited (up to 24hrs) and plugged it back in
  • Let it run for 24hrs to see if it would sort itself out
  • Removed the drives and start up
  • Tried changing ports both on the Mac and the unit 
  • Checked system info - thunderbolt, and it was listed there, although it showed only as connected upstream
  • Disk utility
  • removed and reinstalled com.promise.driver.stex
  • removed and reinstalled the Promise Utility app
  • Removed power cable from UPS and tried directly in wall socket
  • Tried the promiseutil comand line interface (Error (0x4008): subsystem not found)
  • Fully cleaned dusted the unit
  • Tried different rebooting orders (mac then unit, etc)
  • Fully clean and dusted Mac
  • Reset the SMC
  • Reset the PRAM/NVRAM
  • Cleared caches on mac
  • Ran the maintainance scripts in terminal
  • Inserting the disks one at a time
  • Swearing at the unit and callling it names

Thanks in advance for any help or creative suggestions you all can send my way. All of my work is located on those drives and deadlines are looming. If there is something that I've missed (a hidden magic button I can poke with a paperclip would be great) or something I can point to and blame for this. Please let me know.

Cheers!

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Frank Bosma posted this 09 February 2026

Hi Richerd,

probably first thing to check is if the device can mount with a new Thunderbolt cable, especially since you initially encountered random disconnect issues.

Your MacPro late 2013 should have native driver version 6.2.13 installed out of box, so even without other driver installation it should be recognized without any issues.

Kind regards,
Frank

Richerd Reynolds posted this 09 February 2026

Thanks Frank, I will have to try and hunt down a new thunderbolt cable. It seems TB2 cables are pretty rare these days, and if you find one, expensive. Makes me wish I bought a few extras back in the day.

As well, there has been a change. Now when I start up the unit, the drives all spin up, wait a couple of seconds, then spin down. I don't know if that is good or bad, but it is different. Any thoughts? Thanks again.

Cheers!
Richerd

Frank Bosma posted this 09 February 2026

If no Thunderbolt connection is established the Pegasus 2 devices will actually power on for about 10-15 seconds, then power down so it could indeed point to an issue with the cable.

Unfortunately i can't guarantee a new cable will solve your issue and as you mentioned they do seem to be quite expensive at the moment.

Frank Bosma posted this 09 February 2026

Actually, if you live in the US we have the online Promise shop where there seem to be Thunderbolt 1 cables available.

These are compatible with Thunderbolt 2 devices but cap at 10 Gbps per channel. This makes them less useful for 4k highres video streaming but should be ok to use for data transfer and testing your device.

https://promiseshop.promise.com/us/product/Sumitomo_Thunderbolt_cable_0_5M

Richerd Reynolds posted this 11 February 2026

Thanks Frank, but unfortunately, I'm not in the US. I had seen it in the Promise shop earlier and was disappointed  to see that there was only shipping to the US (think I cracked a tooth actually).

Cheers!

R

Richerd Reynolds posted this 3 weeks ago

Okay, finally. An update. I purchased another Pegasus2 R4 and a new thunderbolt 2 cable. I pulled my original drives and swapped them with the 4x2tb drives that came with the newer unit (to be safe) and plugged the new thunderbolt 2 cable into my orginal unit and started it up. The fan came on, the drives spun up, all the relevant lights were blue but the power button stayed orange and there was no activity from the drives. I checked the Promise Utility app and no dashboard. I checked the System Information under Thunderbolt, and the unit was there.

I then plugged my old/original thunderbolt 2 cable into the newer R4 and started it up. All lights were blue, there was disk activity and it mounted. The dashboard came up in the Promis Utility and the system status was all checkmarks. It is great that I have my files again, but I would really like to know/fix what is going on with my original R4. So I am still seeking help in solving this mystery. Right now, the only difference between the two units is the newer one is on an older firmware version (5.04.0000.18). In the MacOS system information the report for the two units are almost identical with the exception of them having different UIDs and the new TB2 cable (connected to original R4) has a serial number and newer cable firmware version.

Thanks again for your help,

Cheers!

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