I'm sure this will not matter to op, but for sake of anyone like me who hits on this page in the future here is one update. I thought...

Nicely done. Looks like good approach for a workaround. Thank you.

Tested this, and you're right, SSISDB does get created in same location as system DBs (not necessarily C: drive). .

Seems to me MS doesn't know whether SSISDB is a...

Nice!

I confirm your results again. Sorry...I never have sourced from a database before--just never occurred to me. I have always used "device" button & then picked backup file(s)....

I see your point. I never use SSMS this way, did not notice that difference. If using SSMS GUI, I generally choose "restore database" from the "databases"...

If you really don't want to change connection strings, then I think you'll need to make instance names the same, D=B. Otherwise should work, we've done it in past.

different security context...possibly the trigger behaves differently for different users?

Even though you think this is unlikely, I think most reasonable cause is SQLAgent service account now lacks sufficient rights (either within SQL or at OS-level). To further diagnose...

I think you're considering right things. If your SAN is powerful and DBs are small, maybe not an issue for you at all.

For boxes with their...

SETUSER is deprecated, and apparently does not work as well as its replacement. This will work: EXECUTE AS LOGIN = 'Other_USERS'

Use REVERT to return to initial security context.

For 2nd question I'm sure best practice is "no", but pretty sure we've done this before. I think it comes down to potential for danger/misuse/tragic mistakes. If you...

I don't know about best practice, hope you get some other replies, I'd like to see them. But I think not good to use your acct--probably too many rights,...

Fully agree with Koen. The DB is created in the default data/log locations, so easiest way to control where it is placed is to set these first. But...

Not me