Mahazarnama- compulsory or not

Yes, 

The mahazar serves as proof of occasion, cause or effect of facts, coming under section 7 and 9 of the Indian Evidence Act. It is a descripttion of facts and state of things which an investigating officer observes in a scene of crime..

The court also relies upon charge sheet filed by the officer.

Without recording along with witness attestation, the recording has least value, it gets easily challenged in court.