I have an m3 large. Although I can find the other EBS volumes associated with that instance in the Volumes Section.
But I am not able to find my 32GB SSD disk.
How can we take backup of this SSD?
It appears that you are referring to the Instance Store SSD volume that is provided as part of an m3.large Amazon EC2 instance.
Instance Store volumes are temporary (aka "ephemeral") and the content is lost when the instance is Stopped, Terminated or fails. Therefore, it is recommended only for temporary files and swap files. Be sure to copy off any data you wish to keep before the instance is Stopped.
Instance Store volumes are not the same as Elastic Block Store (EBS) volumes. While EBS provides a snapshot capability, this is not available for Instance Store volumes.
Instead, you must copy off any data you wish to keep via normal filesystem commands, or run traditional backup software. There is no snapshot-like capability available for Instance Store volumes.