Advice on out of service pages

Another possible approach is this:

1) Create two pools: one with your real site, the other with your splash page.

2) Create a simple iRule to check the member count of your primary pool. If your nodes are down, select your splash page pool and reset the URI to "/".

Something like this (untested, unchecked for typos, etc.) may work:

 
  
 when HTTP_REQUEST { 
   if { [active_members primary_pool] < 1 } { 
    
   Your primary members are unavailable, so crop the URI and select splash page servers 
   HTTP::uri "/" 
   pool splash_pool 
  
   } 
 } 
  
 

Good luck!

-Matt