Will create 64 GB disk and mount it:

dd if=/dev/zero of=cam03.img bs=1M count=64000

Create filesystem:

mkfs ext4 -F cam03.img

Create a mount directory

mkdir /mnt/cam03
chown nobody:nogroup /mnt/cam03

Mount image:

mount -o loop,rw,sync /mnt/MAIN/CCTV/cam03.img /mnt/cam03