Windows 7 Mount Software RAID 5 array

I think you've got it right. Make sure you understand and heed the warnings regarding growing RAID 5 in man 8 mdadm.

Personally if I were growing an LVM volume, I would not be growing an existing RAID array to do it. I'd create another RAID array, create a new physvol from it, and add it to the same volume group. This is a much safer operation (doesn't involve rewriting the whole RAID5 array across the new set of disks) and keeps the size of your arrays down.

16TiB is the maximum volume size with 4K clusters.

You'll need to do one of:

• reformat with a larger cluster size
• change the cluster size to 8K (apparently Acronis can do so)
• create another NTFS volume so you can use that unallocated space. You can then mount that volume onto a folder in your C drive if you prefer having a single drive, but you'll have to remember you still have the 16TB/5TB restriction. (thx for the suggestion 'Multiverse IT')