Bootcamp Partition Oddness

This is normal and expected behavior. On a Mac, when a Hybrid MBR is used to support legacy BIOS/MBR installations, it has two limitations.

1. It supports only four (4) entries.

2. It supports only 32-bit integers. This limits the MBR to 2TB size and 2TB addressable blocks.

BCA assistant locates the Windows partition in the middle of the CS LVG and then spans the two chunks into one. Use Time Machine to coalesce these into contiguous physical disks.

This limitation does not exist on GPT/EFI Macs (late 2013 and later models). W7 has many issues with GPT/EFI and is not used on Macs, but can be installed using GPT/EFI on PCs.

solomani wrote:

I did end up putting the BootCamp partition back with Windows 10. Are you saying that if I do a Time Machine Restore to the HD it will coalesce the partitions without breaking the boot camp Windows 10 install?

Please do not do this. It will definitely break Windows. If you decide to remove Windows, then TM can do this.

Am I right in saying that two partitions in one logical drive makes no practical difference since OSX will treat it as one drive?

There is a difference (to be pedantic). A CS LVG typically uses a 'faster' disk at the head of the CS LV, and remaining one or more disks are 'slower'. There is some block movement between the two parts. In your case, you will have this arrangement on the disk as

Fusion drive without Bootcamp

1. SSD (Faster)

2. OSX (HDD slower)

Fusion drive with Bootcamp

1. SSD (Faster)

2. OSX (HDD Part 1 - slower)

3. Bootcamp (CS unaware)

4. OSX (HDD Part 2 - slower)

This can at times cause delays in fetching blocks during disk IO. In the overall scheme, this is still faster than traditional mechanical disks.