First login to <sid>adm user of hana database

su  - <sid>adm

Execute the below command

HDB start

This executes the HDB program in path /usr/sap/<SID>/HDB<instance no.>/

The below command for stopping also uses same HDB program

HDB stop

One more program that can be used for start/stop of Hana DB is the sapcontrol program located in the path /usr/sap/hostctrl/exe/

The start command is as follows

sapcontrol -nr <instance no.> -function Start

The stop command is as given below

sapcontrol -nr <instance no.> -function Stop