I'm trying to get Win7 working from an external FireWire drive (Macbook pro mid 2009, OSX El Capitan). I've tried the two tutorials below; the installation seems smooth either way and mac recognizes the external hard drive as windows drive after restart (holding option key). But after selecting the windows option, I end up with a "No bootable device – insert boot disk…
1.https://bleeptobleep.blogspot.com/2013/02/mac-install-windows-7-or-8-on-external.html
2.https://blog.macsales.com/40947-tech-tip-how-to-use-boot-camp-on-an-external-drive
Would be fantastic if someone has experience with this and could give me a hint!
Cheers!
Edit: I've now also tried the tutorial here: No bootable device USB 2.0 MacBook Pro mid 2014
I've adapted the Disk and partition IDs to match my system. Same result, after reboot of the mac the external hard drive is recognized as windows partition, but remains not bootable.
Best Answer
The answer is NO. I you are reading somewhere else that this is possible, then either you are being lied to or the instructions are for a different model Mac.
2009 Macs need to BIOS boot Windows. The Boot Camp Assistant assumes you will be installing Windows by using the optical drive. The 2009 model year Macs can not BIOS boot from an external drive.
You can try to EFI boot Windows 7, but I do not believe you can EFI boot Window 7 from an internal or external drive on a 2009 Mac.
Apple eliminated the optical drive in Macs starting with the 2012 model year. In order to be able to install a BIOS booting Windows 7, Apple modified the firmware on these models to allow for BIOS booting of Windows from the USB port. This allowed Windows installer flash drives to boot from the USB port. Eventually, this also allowed a BIOS booting Windows to be installed on USB HDD and SSD. (See this question for an example) However, this required installing without the aid of the Boot Camp Assistant.
Apple eliminated the BIOS software from firmware in Macs starting with the 2015 model year. This effectively ended the ability to install and run Windows 7. Current Mac models only UEFI boot Windows and do not even need a flash drive to install Windows. However, you can still use a flash drive if you wish to install without the aid of the Boot Camp Assistant.