Gorio3721,
My first attempt at the Schwartzian Transform.

#!/usr/bin/perl -w
use strict;

my @keys = qw (CMS5 Drive1 Drive2 Drive10 IRMA1 IRMA13 IRMA2);
my %hash;

@hash{@keys} = ();

for my $key ( custom_sort(\%hash) ) {
   print "Key:  $key\n";
}

sub custom_sort {
   my $hash = shift;
   return
       map { $_->[0] }
       sort {
           $a->[1] cmp $b->[1]
                   ||
           $a->[2] <=> $b->[2]}
       map { [ $_, /(\w+?)(\d+)$/ ] }
       keys %$hash;
}
__END__
Key:  CMS5
Key:  Drive1
Key:  Drive2
Key:  Drive10
Key:  IRMA1
Key:  IRMA2
Key:  IRMA13
[download]

Cheers - L~R