Hello Deepak,
Actually, there are a lot of Oracle bugs that could lead to SCN overflow.
Usually, the toughest part of diagnostics is to find the Oracle instance
that poison the entire database network with the abnormal SCNs.
You may find useful the following script:
https://andreynikolaev.wordpress.com/tools/scn_stats-sql/
It calculates the SCN Headroom history, average daily SCN rates,
and intrinsic average SCN generation rates for the database.
The rogue database has the int_scn_rate >= 16K.
I wrote this script some time ago following the ideas of famous Riyaj
Shamsudeen post
https://orainternals.wordpress.com/2012/01/19/scn-what-why-and-how/
Good luck.
Andrey Nikolaev
Latch, mutex and beyond
http://andreynikolaev.wordpress.com
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