I see 2 questions

1. Well the usual structure for a sorted table is a AoH .

 @space = (
  { node => 1 , "cores" => 12, "memory" => 200 }, 
  { node => 2 , "cores" => 12, "memory" => 500 }, 
  ... 
)
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2. The sort manual describes how to sort for 2 values with an or- combination

my @new = sort { 

       ($b =~ /=(\d+)/)[0] <=> ($a =~ /=(\d+)/)[0]

           || 

       fc($a) cmp fc($b) 

   } @old;
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Maybe try to combine this and show us what you tried. :)