What creates and uses \system volume information\$CBT2 files?

Hi,
I am unable to properly shrink my iscsi drive X: because the file "\system volume information\$CBT2" is marked D (unmovable). I would like to remove that file so I can shrink that volume which now has significant wasted space, but I don't know what it is for and what the side effects of removal might be. I am guessing that it is related to "changed block detection" given its presence on all of my disk volumes. However, I have never used on these disks either Macrium Reflect (which can create $MRCBT files) or any vmware (which I suspect also creates CBT files). So can anyone help me understand there purpose? I am using Windows 10 Pro 2004.
Thanks
Web Dove