Install mhddfs package on a Debian/Ubuntu/Mint Linux

• apt-get install mhddfs  (debian-ubuntu)
• yum install mhddfs (suse)
• dnf install mhddfs (fedora)

Configuration

First, create a new mount point directory called /virtual.data
# mkdir /virtual.data

To join all three drives :
# mhddfs /disk1,/disk2,/disk3 /virtual.data -o allow_other

# df or df -h

# ls -l /virtual.data/