Yesterday I was listening to this "Suppose unnai" song from Sukran. It is a peppy song based on the Hamsadhwani scale. And it set me thinking why this scale is not used in many film songs. Hamsadhwani/Hansadhwani is a janya of Shankarabharanam.

Arohanam: S R2 G3 P N3 S
Avarohanam: S N3 P G3 R2 S

It is a very sweet and pleasant raga. Most of you would have heard of the famous "vathapi ganapathim baje" song set in this raga. However, this is not used much in film songs. I first heard about this raga from my mother while hearing the song "Let me see the love" from "Colonial Cousins" debut album. Film songs in recent times set in this scale are listed below. You may add more to the list.
  1. En manadhai kollai - Kalluri Vaasal
  2. Thee kurivi - Kangalal Keidhu Sei
  3. Vellai pookal - Kannathil Muttham Ittal
  4. Suppose unnai - Sukran
  5. Sriranga ranga - Mahanadhi (interludes and charanam)
  6. Thirakkadha poovukulley - En Swasa Kaatre (starting portions of charanam alone)
  7. Enna paatu - Oru naal oru kanavu
I could only list a handful. The chords for this raga are also very light-music friendly. Chords like C Major, G Major alone are sufficient for this scale. E minor chord can be used at times. Still not many songs are set in this scale. Other ragas like Mohanam are used more than this. Any thoughts?