I think the module Storable can be of help, It has the methods 'store' and 'retrieve' which are direct to work with when storing datastructures to files and returning them back,in addition to other utilities, check the link above...In my Windoze Machine, the DB_File module did not really work for me, so I used this one instead...

use strict;
use warnings;
use Storable;

my %hash;
$hash{"Janet Jones"}     = {
            "spouse"     => "Bob Jones",
            "son 1"    => "Tom Jones",
            "son 2"    => "Pete Jones",
            "pet 1"    => "Boyle",
            "father"    => "Richard Smith",
            "mother"    => "Fran Smith",
            "sister 1"    => "Louise Williams",
            "address"    => "1 Main St, Littleton, PA, 55555",
            };
            
$hash{"Bob Jones"}    = {
            "spouse"     => "Janet Jones",
            "son 1"    => "Tom Jones",
            "son 2"    => "Pete Jones",
            "pet 1"    => "Boyle",
            "father"    => "Paul Jones",
            "mother"    => "Stella Jones",
            "brother 1"    => "Paul Jones, Jr",
            "brother 2"    => "Vince Jones",
            "brother 3"    => "Dan Jones",
            "sister 1"    => "Andrea Limux",
            "address"    => "1 Main St, Littleton, PA, 55555",
            };

store(\%hash, "HashOfHashesFile.txt");
my %friends = %{retrieve("HashOfHashesFile.txt") };
for my $name (keys %friends){
        print "$name->\n";
        for my $info(keys %{$friends{$name}}){
                print " " x length("$name");
                print "$info->  $friends{$name}{$info}\n";
                }
        }
[download]

OUTPUT:

Janet Jones->
           spouse->  Bob Jones
           son 1->  Tom Jones
           pet 1->  Boyle
           mother->  Fran Smith
           father->  Richard Smith
           address->  1 Main St, Littleton, PA, 55555
           son 2->  Pete Jones
           sister 1->  Louise Williams
Bob Jones->
         spouse->  Janet Jones
         son 1->  Tom Jones
         brother 3->  Dan Jones
         pet 1->  Boyle
         mother->  Stella Jones
         brother 2->  Vince Jones
         father->  Paul Jones
         brother 1->  Paul Jones, Jr
         address->  1 Main St, Littleton, PA, 55555
         sister 1->  Andrea Limux
         son 2->  Pete Jones
[download]

This link to a Wikipedia article is very informative of the concept of data serialization..