Pagasus2 R4 Bootdisk problems macOS Sierra

  • Last Post 08 March 2017
Egon Bulten posted this 15 February 2017

It amazes me that I can't actually find relatively few reports about our problem!

We have a Mac Mini and iMac that both boot from a Pagasus2 RAID through thunderbolt because both machines are used as a server! Since Apple does not make servers anymore this is actually our only solution!

We have the iMac and one Pegasus2 just purchased new from Apple and we could not select the Pegasus as Boot Drive for MacOS Sierra from out of the box! We thought at first that it was a hardware problem but after some googling we found out that Apple has switched off this option to boot MacOS Sierra from a Thunderbolt Drive! (Thanks for ruining our servers UlfFrisk)

Our new iMac came with macOs Sierra 10.12.2 and the new EFI so no solution for this setup! And for the Mac Mini Server, just cancelled the updates just in tIme and never switch off and hope there will be no power failure...

My question to Promise: "FIX THIS PLEASE!!!!!" so we can use our Pegasus2 as a RAID Bootdrive again!!!


Best Regards


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Egon Bulten posted this 08 March 2017

Nothing is working and I will return the Pegasus R4! So it isn't working as fine with Mac as Promise is advertising!

Egon Bulten posted this 22 February 2017

Tried all the fixes supplied by Apple and only our Mac Mini Server (late 2014 model) could be saved!

But for our iMac Server (late 2015 Model) it's too late and no fix! So my question to Promise would be: "FIX THIS!!!!

Or i will have to return it and buy an other RAID Drive!

philippe menegatti posted this 19 February 2017



same issues on all my Macs (iMac, Macbookair) since I update from Sierra 10.12.2. to 10.12.3

2R4 Working fine before, no more access to the drive since, even through Promise Utility

Can't be seen anymore

Hope Promise will issue upadated driver soon

Regards, Philippe

Devendra Kumar posted this 15 February 2017

Hi Egon,

There is a temporary fix from Apple 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:

See if it works



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