Installing Windows on USB/External

[Sionic Ion]

Ok so you want Windows 7 to run off external HDD?

Do it all the time. :) I'll make it short and you can ask for help in detailed steps in case you can't figure it out.

So create a VHD on internal HDD, cannot be dynamically expanding if you want the utmost top speed. Then load up Windows 7 install, load up CMD via repair options, then go into diskpart and select the VHD and then mount it. After that, simply install it. Windows 7 install will set it all up for you. :) It will do it's job and make it bootable (Windows 7 introduced native-boot VHD capabilities).

Then once booted up, download and install utility called PWBoot which will make the VHD install portable. Boot back into Windows, copy and paste the VHD to external HDD formatted with NTFS, and then use EasyBCD to make external HDD bootable and create a BCD store for it, and then create new boot entry with name like TEMP and find VHD and make it portable entry, it'll fail, click the checkmark to continue running EasyBCD regardless of error, then add new entry called Windows 7 and find VHD and make it portable entry, it'll work this time. Then delete the TEMP boot entry. (EasyBCD has a bug with empty BCD stores, has to be at least one entry before adding a working one...just a bug.)

Boot off external HDD, and it should boot as usual. Also, it is not very portable, it has an attitude, so don't plan on running it on many other computers.

I now use Windows 8's portable workspace feature which doesn't need a VHD and installs it right to external HDD, and it works on Intel and AMD systems. ;)

[Sionic Ion]

Using this on a Mac though may need potential modifications to how you set it up. But it should be entirely possible. For example, you'll need a virtual machine or bootcamp or existing PC with Windows to use EasyBCD. Also, EasyBCD might not work in creating a functional BCD store on an EFI-based system, maybe you have to set the partition table to GUID and then EasyBCD will create it correctly.

Either way, USB isn't as slow as many people think it is... :p In fact I think it's pretty decent. :yes:

[Dinggus]

I would do what you recommended, but don't I need a CD-Rom drive to do that? What are repair options and diskpart?

[Sionic Ion]

I would do what you recommended, but don't I need a CD-Rom drive to do that? What are repair options and diskpart?

That's part of the Windows 7 Install.

[justusthyme]

I have cloned my Windows 7 drive onto a SATA drive connected via USB to the computer. I applied the PWBoot patch to the external drive. Then removed the internal master drive, booted the computer and the USB drive with Windows 7 executed perfectly. This solves a huge problem for me.

Does anyone know exactly what PWBoot adds or changes to allow the external USB drive to boot? Is it changing .sys files or changes to the registry, if yes, what are the changes?

I would like to manually try the changes on my next drive.

[winrez]

Windows 7's Boot to VHD should work if the Mac's EFI supports it.

here is a guide http://www.markwilson.co.uk/blog/2009/10/native-vhd-boot-windows-7-or-server-2008-r2-from-an-external-usb-drive.htm

sorry didn't see Sionic Ion's post

[game_over]

Old thread i know but did this get any easier with Windows 8? I've picked up a USB/Thunderbolt external HDD so it should be fast enough to run a copy of Windows then i could scrap my old windows laptop all together as i only use it for 1 or 2 tasks.

[edit] quick google brings up a few results mainly holding down alt when switching on mac brings OS selection, this is fine as a last resort but i'm wondering if there is a way i can boot it within OSX so i can easily switch between the 2, without it taking up much space on the internal disk.

Internal: files to run/boot windows

External: OS files

Also, how much space does W8 take up?