When I originally set up my Boot Camp partition I just picked a split of 50% for each drive – 256GB for OSX Mountain Lion and 256GB for Windows 8. After settling into Windows 8 and not really being very interested in OSX I wanted to allocate more space to the boot camp partition. I thought it would be simple and in the end it was, but the first things I tried didn’t work.
The following steps worked for me:
- In OSX shrink the ‘Macintosh HD’ volume using the native Disk Utility.
- Reboot into Windows 8, schedule a chkdsk /f and reboot.
- Using MiniTool Partition Wizard Home Edition 7.6 I extended the ‘bootcamp’ volume hosting Windows to use this new unallocated space freed up when shrinking the OSX volume.
I originally tried using the native Windows 8 disk management utility but it is not able to ‘extend’ the Windows volume. This didn’t work however because the free space is to the left of the volume, not the right. The use of this Partition Wizard tool gets around this as it is able to extend the volume to the left.
Previously I had tried CampTune but it didn’t work – I suspect it doesn’t support Windows 8 yet.
If you want to learn more about the OSX Disk Utility program I suggest reading this. And for a guide to some of the other techniques for resizing your Boot Camp partition I suggest reading this guide.