GDFS Backup!!

[simox]

Can anyone clearly in layman's language tell me what is GDFS file?

First of all read this: SonyEricsson Hardware and Firmware Definitions!

How do you get to know that GDFS file is corrupted or is damaged?

Well, there are several symptoms. For e.g. after flashed the phone and turned on it is stuck at please wait screen. And if you mod your phone, the first thing is to make a GDFS backup.

If after flashing the phone is getting on, does it mean that GDFS is safe?

In this case, most probably the GDFS is OK.

After flashing your phone to a new firmware does the GDFS file remains the same or it gets changed?

The GDFS will remain, because you flash the MAIN, FS and not the GDFS.