I'm after some advice. I asked the question below in good faith but it's been closed (as non-constructive) and I'm at a bit of a loss in figurng out how I can ask it the right way. Any help appreciated.
This one failed the "too broad" test, as there is no one true answer and could get a lot of brain-stormy answers. In short, it's focus is very open ended rather than narrow. Questions phrased like:
What are some common issues that affect...
Do badly here. Questions here need to be about one or a small set of already known issues that we can help resolve.
I'm not sure how to change your question to fit seeing as you're looking for "what have I missed" kinds of things.
It's really hard to definitively answer the kind of question you're asking.
The crux of what you want to know is summarized toward the end of your question:
In what ways could an application fail that require "some time" to get the application back up and running (but not so fatal that DR [was] invoked)?
And the answer is "It depends" (on, among other things, your application, its failure modes, your downtime tolerance, and your DR plan).
We could give you lists-of-things, but those lists are always going to be vague and incomplete.
Conversely if you come up with the list yourself (see the comment I left on the question for a point in the right direction) you'll have a better starting point to understanding what could go wrong and how you want to react (fix, flee (to DR sites), or F it all and sell the company).
Now once you've done a FMEA or fault tree analysis you'll probably have some new items you hadn't thought about ("What happens if a squirrel gets into the datacenter and chews through all the fiber cables?!") -- Those we can probably help you with, as they're more specific and narrowly scoped.