Updating the firmware of a Promise Pegasus R4 RAID

If you have one of these Thunderbolt external RAID arrays, it is easy to let its firmware get quite out of date. Like me, you probably don’t run the Promise Utility unless there are problems; if you don’t have any problems for a good while, chances are that neither that app nor you have checked for updates.

Another snag is that the app doesn’t always install the updates which it says it will. I first updated the Promise Utility itself, to the current version 3.20.0000.15 (C03). It then kindly informed me that there was a firmware update, it downloaded the update, and claimed to have installed it for me. When updated in this way, you then have to shut the RAID unit down, and start it up again, for the update to take effect. And it didn’t: the firmware version was reported as being unchanged.

So if you want to update the firmware in your Promise RAID, don’t leave it to the app.

Instead, visit the support page, make your way to the Pegasus Series – Pegasus R4 listing, locate the firmware, and download it as a .img file. Then open the Promise Utility, and select the Firmware Update command from its Admin menu.


Click on the Choose File button, locate that .img file, then click on Next to proceed with the update. You will then have to confirm that you want to update, and ensure that nothing shuts the system down during that process.


Once complete, press and hold the Power button on the Promise unit until the button light changes from blue to red. Release, and the unit shuts down. After a few seconds, press the Power button again to start the unit up, and the firmware should now be fully updated.