There are lots of steps involved in BW to HANA migration :
Check BW on HANA Cookbook :
https://cookbook.experiencesaphana.com/bw/what-is-bw-on-hana/how-get-it/adoption-options/
Check this blog :
http://www.saphana.com/docs/DOC-3294
Check other threads :
http://scn.sap.com/thread/3322420
http://scn.sap.com/thread/3213305
BW on HANA Migration stepshttp://scn.sap.com/thread/3191919
http://scn.sap.com/thread/2120728
Also check the following Notes :
1514967 SAP HANA: Central Note
1018839 Admin (HANA)
1514966 Sizing SAP HANA Database
1523337 SAP HANA Database: Central Note
1598623 Security
1599888 SAP HANA: Operational Concept
1637145 SAP BW on HANA: Sizing SAP HANA Database
1729988 SAP BW Check for HANA Migration
1736976 Sizing of BW (Using an ABAP Report)
1712334 - Important Notes for SAP BW powered by HANA on SP7
If you are going to move SAP System database to HANA, then you can refer :
https://cookbook.experiencesaphana.com/erp/b0652754cba44f88851a005a4d904ef2.html
You can also check this presentation : http://scn.sap.com/docs/DOC-40169