I'm not normally one for blog series. Call it a short attention span, call it an old style approach to blogging, call it what you will but I tend to write about whatever is currently on my mind. Never the less what is on my mind at the moment is the application of Oracle's released Critical Patches to an E-Business suite infrastructure with none applied. I'll be presenting on this subject at theUKOUG in December so if you want to tell me just how badly we did it then catch me there. This topic is rather too long for a traditional blog post, and whilst I do intend to write this up as a longer article - to go with the presentation - I thought I'd try a short series working through the steps.

This post will cover the procedure used by the author for applying the critical patch updates (CPU) released from Jan 2005 up to April 2007.  This series is based on an Applications system with ATG Rollup 5 (metalink registration required) already applied. Whilst the general approach in this paper is likely to be widely useful, individual software levels will mean that precise details of patches required will vary from site to site. This is another way of saying - don't take my list of patches as gospel.

The broad approach I took was as follows. - This will serve as a useful road map for the series by the way. 

1. Obtain a List of all patches issued as CPU.
2. Determine any prereqs required.
3. Obtain patches
4. Review all readmes
5. Upgrade databases to current patch level where appropriate
6. Apply CPU updates to tech stack (OID/IAS, DB, 806_HOME. IAS_HOME)
7. Merge the Apps patches for quicker application

 When I reviewed the various CPU documents on Oracle.com websites (metalink and the main oracle.com CPU site) I realized that the list was way too long! Our architecture looks a bit like the diagram below (where the black boxes are the databases - blame the conversion from visio to png for that.

Consequently I decided that a control spreadsheet was needed that could be updated as the process went on. At the start it looked like this. That's a lot of work to get through. Over the next few parts we'll work through how it went and what we learned along the way.