"Two stage" upgrade of Grid Infrastructure 11g->12c

There is pretty interesting and reliable option to install "GI software only" in advance. I use it in order to make sure that relink or patch conflict issues will not cause troubles in critical time. As result, only configuration steps need to be processed in critical time, reducing risk of failure and stress.

Preparation for 12c Grid Infrastructure (GI)

In advance to standard GI12c prerequisites be aware that:

• AMS 12c will require at least 1GB for SGA. Add RAM, or adjust database configuration in order to avoid memory swapping after start of 12c.
• database -MGMTDB will be stored in ASM disk group where OCR is stored. -MGMTDB will take about 6GB. If you use small OCR_DG, you will encounter space saturation of this diskgroup after start of production with GI12c, soon.