Here is a revision of your code that correctly finds the chunks, and counts ID's.
Since ID's are the same in your sample data - I leave hashing the found ID's as an exercise.

#!/usr/bin/perl

#use DateTime;
use strict;
use warnings;

my $LOGFILE = 'parsechunk.data';
local $/ = "\nrn:";
my $x=0;
open(my $LOGFH,"<",$LOGFILE) or die("Couldn't open '$LOGFILE:$!");
while(<$LOGFH>) {
   #chomp;
   print $_, "==RECORD END++\n";
   my $id_count = () = m/(id-info:)/og;
   print  " Found $id_count ID's in last chunk\n";
}
close $LOGFH;
[download]

Update: Added "close $LOGFH;" ... because I'm a nice guy and like to keep the OS happy, and my code clean/complete.