How have you accumulated historical data over time?

TradeTastic

This is for all traders and systematic trading folks who run automated/ semi automated systems - how do you do the following?

- Run Backtesting on Options?
- How did you get past historical data, say NSE, BSE and MCX from the beginning (1 min OHLC and OI) data

Please share some ideas/directions so that I can also figure out a way to source the data and build systems as necessary