I removed the ^ and $ notations in your regex, and your matching worked perfectly:

#!/usr/bin/perl

use Modern::Perl;

my @matched =
  qw {pv_name alt_link pv_status total_pe free_pe autoswitch proactive
+_polling};

my $vg_details = '
   --- Physical volumes ---
   PV Name                     /dev/dsk/c14t3d1
   PV Name                     /dev/dsk/c15t3d1 Alternate Link
   PV Status                   available                
   Total PE                    15997   
   Free PE                     0       
   Autoswitch                  On        
   Proactive Polling           On               
';

$vg_details =~ m/^\s*PV\s+Name\s*(?<pv_name>\S+)\s*
    (\s*PV\s+Name\s+(?<alt_link>\S+)\s+Alternate\s+Link\s*)   # skip t
+hem
    \s*PV\s+Status\s+(?<pv_status>\S+)\s*
    \s*Total\s+PE\s+(?<total_pe>\S+)\s*
    \s*Free\s+PE\s+(?<free_pe>\d+)\s*
    \s*Autoswitch\s+(?<autoswitch>\S+)\s*
    \s*Proactive\s+Polling\s+(?<proactive_polling>\S+)\s*/gsmx;

say $+{$_} for @matched;
[download]

Results:

/dev/dsk/c14t3d1
/dev/dsk/c15t3d1
available
15997
0
On
On
[download]