Pegasus2 R2 not readable by El Capitan

  • Last Post 21 December 2016
Graham Johnson posted this 19 December 2016

I connected my brand new Pegasus2 R2 to my Mac Book Pro running OS X El Capitan (10.11.6). It did not go through any type of automatic initialization when connected. The Promise utility regonizes the drive, but my Mac does not. There is no icon on the desktop. When I start computer with drive attached, it says it's "not readable by this computer" with options to initiatlize. The Apple disk utility says the drive is unitialized. Should I format using Apple disk utility? Not sure what to do. There is no data on the drive so no concerns there...

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Graham Johnson posted this 19 December 2016

Devendra Kumar posted this 19 December 2016

Hi Graham,

Please follow the below step and see if it works.

To initialize a logical drive:

1. Click on the Background Activities icon. The list of background activities appears.
2. Mouse-over Initialization and click the Start button.
3. Check the box to the left of the logical drive you want to initialize.
4. Choose Quick initialization option and enter the a value in the Quick Initialization Size field. This value is the size of the initialization blocks in MB(you can enter 10) and confirm

* Access settings below the Background activities section and set the Init Rate to 'High'. The Initialization will take couple of hours to finish.

After Initialization is complete, To format your logical drives using the computer’s disk utility:

1. Click the Go menu and choose Utilities from the dropdown list.
2. Double-click the Disk Utility icon to open the utility.
3. In the drive list, highlight the logical drive you want to format and click the Partition button.
4. Make your Volume Scheme, Volume Information, and Options settings and click the Apply button. For Macintosh computers, the default GPT Format partition and the default Journaled HFS+ format are recommended.
5. In the Confirmation dialog box, click the Partition button.


Graham Johnson posted this 19 December 2016

I assume the 'Background Activities' icon is in the Promise utility? Sorry - can't find it...


Peter Guentert posted this 20 December 2016

Question: Did you install the security patch 2016-003?

That changed some EFI settings and since then, my R6 does not boot from the MacPro.

Olaf Seifert posted this 20 December 2016

For us, this no-boot-problem came up when we updated to macOS 10.12.2 – not with El Capitan but Sierra. Apple changed something in EFI for security reasons. Have a look:

I opened a case at PROMISE support. They are aware of this issue and are working on it.


Maybe any update will help the original problem of this post, too.

Joris Piepers posted this 21 December 2016

There is a temporary fix from Apple for MacOS 10.12 (Sierra) which need to be executed from terminal/ command line (as admin/ root):

nvram enable-legacy-orom-behavior=1

You can undo the command by running the command from terminal/ command line:

nvram -d enable-legacy-orom-behavior

The command will allow you to boot from non enabled EFI devices.
Original knowledgebase article: