11gR2: Bug causes RMAN to remove spfile during database upgrade

The title of MOS document "Upgrade Of Database From 11.2.0.1 To 11.2.0.4 Caused RMAN Duplication To Error On Spfile" from article ID 1951266.1 tells us about a bug which needs to be avoided during 11gR2 upgrades with either a workaround or one-off patch.

Weekend Learning: ASM not starting after upgrade to 11.2.0.4

My Oracle Support article ID 2006534.1 has note "ASM fail to start with error ORA-00132 After Upgrade From 11.2.0.3 To 11.2.0.4" which has a very simple solution to the problem.  Now my next challenge is to understand why the spfile has to be modified in the way Oracle suggested!

Frits Hoogland: DB parameters from spfile

I've mentioned a few of Frits' articles before, and while this one may be a little out in left field for somebody in a Support role that never really gets to deal with pfile/spfile or even ASM, I think it is a good exercise to follow along with!  Frits has a shortcut to use ASM to get the information out of a spfile using the strings command, but as you will see shortly something is not 100% correct so he goes digging into the guts of how Oracle is working with the spfile to come up with a very interesting (and probably right) hypothesis.