want to access single value in a hash

[Sunita Pradhan]

I have following data structure :
my $cmd_param_show = {'scsitrace_start_log_to_disk_true' =>                     
    {'param_val'=>{'log-to-disk' => 'true'},                          
'scsitrace_show' => {'log-to-disk'    => 'true',                                
            'enabled'        => 'true',                                         
   'max-chain-size' => 16,                                            
'max-file-size'  => 0}},                  'scsitrace_stop' =>                   
{'param_val'=>{},                    'scsitrace_show' => {'log-to-disk'    => 
'false',                                            'enabled'        => 
'false',                                            'max-chain-size' => 16,     
                                       'max-file-size'  => 0}},                 
  'scsitrace_start' =>                    {'param_val'=>{},                     
'scsitrace_show'  => {'log-to-disk'    => 'false',                              
              'enabled'        => 'true',                                       
     'max-chain-size' => 16,                                            
'max-file-size'  => 0}},                   'scsitrace_dump' =>                  
   {'param_val'=>{},                      'scsitrace_show' => {'log-to-disk'    
=> 'false',                                            'enabled'        => 
'false',                                            'max-chain-size' => 16,     
                                       'max-file-size'  => 0}},                 
                          };
How can I access single value from this hash without using loop ? 
I tried to print like :print 
"%{$cmd_param_show}->{'scsitrace_start_log_to_disk_true'}->{'param_val'}\n";
It failed .Please help me to get this.
ThanksSunita