Here are the xbpartitioner steps that have worked for me without corruption on 750 GB hard drives:
NOTE: Backup your files before doing this! This WILL wipe both your 'F' and 'G' drives!
1. Execute xbpartitioner
2. Highlight the 'F' drive (Partition 6) and click down on the RIGHT analog stick to disable that partition
3. Highlight the 'G' drive (Partition 7) and click down on the RIGHT analog stick to disable that partition
4. At this point both the 'F' and 'G' partitions should both be disabled. Now, press the START button and then the Y button to confirm the disabling/deleting of those partitions. Now, click the BACK button (Next to the START button) and press A to quit xbpartitioner.
5. Execute xbpartitioner again
6. Both the 'F' and 'G' drives should still be disabled, so now just highlight the 'F' drive (Partition 6), and press the A button to cycle through the common partitioning setups, and once the 'F' and 'G' drives are equal (same size, they should both be about 360 GB) press the START button and press Y to confirm.
7. Now, both your 'F' and 'G' drives will be formatted with 32k clusters. Once it finishes, just press the BACK button (Next to the START button) and then press A to quit xbpartitioner.
And you're all set! No corruption will occur now, as both drives are below 512 GB, and they are also formatted with 32k clusters. I have tried this method many times, and I have yet to see any corruption.
