iRule for starts with "reports/" data group?

Yes, the "strings tolower" built-in TCL command will convert the string to lower case. So, if you "string tolower" the HTTP::uri you will want all your strings in your Report_Strings data group to be lower case.

But if all you want to do is to match all uri's that start with "/reports/" then why don't you just use a simple string comparison with the starts_with operator?

when HTTP_REQUEST {
  if { [string tolower [HTTP::uri]] starts_with "/reports/" } {
    pool RP_pool_1
  }
}

-or- you could use a switch statement and string globbing

when HTTP_REQUEST {
  switch -glob [string tolower [HTTP::uri]] {
    "/reports/*" {
      pool RP_pool_1
    }
  }
}

-Joe