AWS EBS Volume Disapearing

I am not sure if I can ask this question in Stackoverflow.. but Hopefully I can get an answer from here..

I am currently using an EC2 instance in AWS.. and attached 10GB EBS Volume to it.

xvda2 is the volume for ec2 instance and xvdf is the volume that is attached to ec2 instance.

xvdf contains all important application data that I am using.. it in in /mnt/my-data..

The problem is.. when I stop the EC2 instance and restart.. volume get unmounted.. when is run lsblk, my volume is still there.. but when I run df -h... it is not there..

So I am thinking it is attached.. but keep getting unmounted.. Also when run mount command all the time after restarting.. sometimes my files or directories are gone..

is this normal thing in EBS volume? Do I have to keep mounting the volume after restarting an instance?

I used http://ift.tt/1eVhC94 link to attach and mount my ebs volume