Here's some recursion leveraging a sub.

#!/usr/bin/perl

use strict;
use warnings;

my $dir = "/path_to_nas/data/";
my @directories;

find_dirs($dir);

sub find_dirs {
    my $dir = $_[0];
    for my $worker (glob("$dir*")) {
        if (-d $worker) {
            push $worker, @directories;
            find_dirs("$worker/");
        } else {
            # don't care.. standard file.
        }
    }
}

print scalar(@directories), "\n";
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