Big IP Maintenance Page - Multiple Pool Check.

You're going to three separate pools, which could each independently be down. Maybe something like this makes more sense?

when HTTP_REQUEST {
    switch -glob [string tolower [HTTP::uri]] {
        "/uriX/uriZ" -
        "/uriX/uriZ/" -
        "/" { 
            HTTP::respond 301 "Location" "https://www.websitename.com/uri/uri/uri" 
         }
        "/abc.def*" { 
            if { [active_membes poolnameA_pool] > 0 } {
                pool poolnameA_pool 
            } else {
                HTTP::respond 200 content [ifile get "poolname_MaintenancePage_ifile"] noserver "Content-Type" "text/html" "Cache-Control" "no-cache, must-revalidate"
                return
            }
        }
        "*/xyz/*" { 
            if { [active_membes poolnameB_pool] > 0 } {
                pool poolnameB_pool 
            } else {
                HTTP::respond 200 content [ifile get "poolname_MaintenancePage_ifile"] noserver "Content-Type" "text/html" "Cache-Control" "no-cache, must-revalidate"
                return
            }
         }
        default { 
            if { [active_membes poolnameDefault_pool] > 0 } {
                pool poolnameDefault_pool 
            } else {
                HTTP::respond 200 content [ifile get "poolname_MaintenancePage_ifile"] noserver "Content-Type" "text/html" "Cache-Control" "no-cache, must-revalidate"
                return
            }
        }
    }
    HTTP::header insert HttpsIndicatorHeader True
}