my %data;
# By record:
$data{'Drive C'} = {
   'Used Space OID' => '1.2.3.4.5.1',
   'Size OID' => '1.2.3.4.6.1',
   'Max Size' => 200000,
   'Alocation Units' => 4096,
};

# By field
$data{'Drive C'}{'Used Space OID'} = '1.2.3.4.5.1';
$data{'Drive C'}{'Size OID'} = '1.2.3.4.6.1';
$data{'Drive C'}{'Max Size'} = 200000;
$data{'Drive C'}{'Alocation Units'} = 4096;

##</code><code>##

foreach(sort keys %{$data{'Drive C'}}) {
    print "$_ = '$data{'Drive C'}{$_}'\n";
}

##</code><code>##

my $h = $data{'Drive C'};
foreach(sort keys %$h) {
    print "$_ = '$h->{$_}'\n";
}

##</code><code>##

$data[1] = {
   'Used Space OID' => '1.2.3.4.5.1',
   'Size OID' => '1.2.3.4.6.1',
   ...
}

$data[1]{'Used Space OID'} = '1.2.3.4.5.1';