makelifeasy:
I still don't get the idea on writing environment and trying to catch it up; in layman's term, having CR3032 Shield would protect my data from power failure or it would still remain?
In broad terms, what you write to the Battery Backed RAM will be protected from loss by the battery, and could survive for years. But you want it in EEPROM, especially as that has much more space.
You therefore create a system which writes the data as you collect it to the BBRAM. Every so often, either when you have collected a certain number of events (BBRAM is full, or nearly so) or else after a certain period of time on which you have decided, you write this information to the EEPROM. Only when you have checked that the information has been completely written to the EEPROM, do you wipe the BBRAM clean, ready to collect more data. You check this by writing a serial number to the BBRAM and (only after all the data has been written and checked) to the EEPROM, if the serial numbers are equal when you do the check (which you have to do whenever the power has been lost), then the EEPROM is up to date and you can clear the BBRAM to collect more data.
If data occurs whilst the power is off, well, you lose it.