If you want to add new HDD to existing Linux virtual machine like CentOS 7 / RHEL 7 you must:
First add new disk in preferences of virtual machine.
Click Edit preferences of virtual machine. On tab Hardware click Add button and fill proper preferences.
When you save data new hardware should appear on hardware list.
Now login to your virtual machine and execute:
# fdisk -l
You should see all previous mounted hardware.
Now identify host bus numbers by typing:
# ls /sys/class/scsi_host/
in return you should receive list:
host0 host1 host2
Now you must rescan the SCSI Bus to add new devices:
# echo "- - -" > /sys/class/scsi_host/host0/scan
# echo "- - -" > /sys/class/scsi_host/host1/scan
# echo "- - -" > /sys/class/scsi_host/host2/scan
In many cases should be enough scan last SCSI device.
Next verify if new disk appear on fdisk’s list by typing:
# fdisk -l