Hi, I have a rather interesting problem in that I'm trying to get osx 7.5 to boot in diskboot mode from a promise pegasus2 drive.

The macbook pro (2013) and the DAS are both new byweeks. Both work perfectly. To test the booting capabilities of the DAS over thunderbolt2 I used a clone of my old macbookpro hard drive runing osx 10.9 and it workked like a charm. The laptop booted up without a hitch. I then removed the systems disk from my old mac Pro 1.1 which runs 10.7 and tried to boot it the same way. I got the grey screen and with the white "no go" symbol.

I then cloned the old MAc Pro disk onto a new disk larger capacity disk and tried booting from that. Again, no such luck. I then reformatted the original old MAc Pro disk and installed 10.9 onto it with the idea that onced it booted i would then migrate my stuff off the clone. After the instalation the disk with the new instalation of 10.9 has now refused to boot as well.

If I remove the thunderbolt cable the Macbook pro boots up normaly and whne I reconnected the DAS and selected the old macbook pro disk to boot from it does it as before.

ITs that when I try and boot from the old MAC Pro disk (with and with out a copy of 10.9) it will not boot , and when I try and boot from the clone of the old Mac Pro osx disk it will not boot either.

Anyone have any ideas?