my @rec;

while (<$fh>) {
    push @rec, $_;

    if (/^Metadata:/) {
        do_something_with_record(\@rec);
        @rec = ();
    }
}
[download]

Maybe just setting your "record separator" ($/) to Metadata: 1114890 will give you what you want? Otherwise, you will need to show a bit of code and a bit of representative data. Potentially two nested loops might also help, one outer loop to process the records and one inner loop to collect lines up to the next /Metadata/.

1. Since you know the record length, you could use an external counter and read them in, appending them to the end of the last record read:

   my $count = 0;
   my @records = ();
   while (<IN>) {
       if ($count) {
           $records[-1] .= $_;
       } else {
           push @records, $_;
       }
       $count = ++$count % 6;
   }
   print join("\n",@records);
   [download]

2. You could slurp the file and split on a pattern that matches the last line:

   my $content = do {
       local $/;
       <IN>;
       };
   my @records = split /(?<=Metadata\: 1114890\n)/, $content;
   [download]