While I agree that ideally you'd run two IRIS nodes in two geographically close but fully separate datacenters, running IRIS in a mirror with both servers in the same datacenter still provides protection from:

  • Server hardware failure
  • OS-level failure
  • IRIS failure

In addition to that datacenters often allow users to specify placement strategy. Select spread placement strategy to avoid hosting both servers on the same underlying hardware if possible.

So mirroring in this scenario still provides a lot of advantages.

There are to valid ways to solve this code golf:

  • Create a program that contains all ASCII characters in the source code (so it does not have to print anything)
  • Create a program which prints ASCII characters not present in a source code

Both approaches are valid, sample solution uses approach 1.

"Print out" is any output the program produces so if you for example add 1/0 at the end it might save you a few characters.