you are creating a new volume, so are supposed to format the EBS volume with a file system after your step 1. Try this, entire process with your sample mount point is:
Create EBS volume.
Attach EBS volume to /dev/sdf (EC2's external name for this particular device number).
Format file system /dev/xvdf (Ubuntu's internal name for this particular device number): sudo mkfs.ext4 /dev/xvdf
Note:- You should format a file system only if it is a new volume with no data. After Formatting it is very difficult or impossible to any data that was on this volume previously.
4. Mount file system (with update to /etc/fstab so it stays mounted on reboot):
sudo mkdir -m 000 /vol
echo "/dev/xvdf /vol auto noatime 0 0" | sudo tee -a /etc/fstab
sudo mount /vol
I hope this helps you:)