open(FILE, "< $FILE") or die "ERROR: $!";
    my $data;
    {
        local $/=undef;
        $data=<FILE>
    }

    while ( $data =~ m{<DataRecord>(.+?)</DataRecord>}sg ) {
        my $rec = $1;
        if ( $rec =~ m{\d+/\d+} ) {
            push @cache, $rec;
            print "$rec";
        }
    }

    close (FILE);

##</code><code>##

$ test.pl

        <Data>123456</Data>
        <Data>123456</Data>
        <Data2>123456</Data2>
        <Data>1234/3456</Data>
        <Data>123456</Data>
        <Data>1234/3456</Data>
        <Data3>123456</Data3>
        <Data>123456</Data>