Oracle think initially think this ORA-600 error was hardware related
There are NO indications of any hardware fault - the primary keeps running
After a couple of weeks it was decided this was a “bug situation”
This was bug 4767278 which talked about FAL not being able to read from multiple mirror sides when encountering invalid/stale redo in a file. Apparently required for ASM configurations because ASM does not guarantee all mirror sides contain same data after writing.
We were using ASM, but external redundancy
Oracle then said “The ASM group is not 100% sure if the patch 4767278 will fix the problem”