Here is what I ended up doing. I like CountZero solution below. That is much convenient. Cheers, 
use warnings;
use strict;
use Time::Local;

my ($ReadOp, $WriteOp);

while (<DATA>) {
next if ($. == 1);
chomp;   
my @output = split/,\s?/;
if ( $output[2] eq "W" ) { 
    $WriteOp -> {$output[1]}{$output[4]} += $output[3];
} elsif ( $output[2] eq "R") {
    $ReadOp -> {$output[1]}{$output[4]} += $output[3];
}

}
print "=======\n";
print "WriteOperation\n";
print "=======\n";
for my $ip(keys %{$WriteOp}) {
    my $files= ${$WriteOp}{$ip};
    for my $file(keys %{$files}) {
        print "$ip => $file => ${$WriteOp}{$ip}{$file}\n"; 
    }
}

print "\n\n\n";
print "=======\n";
print "ReadOperation \n";
print "=======\n";
for my $ip(keys %{$ReadOp}) {
    my $files= ${$ReadOp}{$ip};
    for my $file(keys %{$files}) {
        print "$ip => $file => ${$ReadOp}{$ip}{$file}\n"; 
    }
}

__DATA__
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4964,/export/file1.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4964,/export/file2.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4963,/export/file2.log
Sun Aug 21 12:08:21 2011,172.22.112.141, W, 9292,/export/home/another.
+file
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4964,/export/file2.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 2493,/export/file1.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 2355,/export/another.log
Sun Aug 21 12:08:21 2011,172.22.32.28, R, 25,/export/another.log
Sun Aug 21 12:08:21 2011,172.20.220.38, W, 3699,/export/file2.log
Sun Aug 21 12:08:21 2011,172.20.220.146, W, 1996,<?>
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 2776,/export/file1.log
Sun Aug 21 12:08:21 2011,172.22.32.28, R, 26,/export/file1.log

[download]

==============================

Hello gurus,

I have some raw data as following. How can I aggregate them to a report format, so that we can see total data transferred from which IP to which file. I consider using reference to parse the original data. What is the data structure I should use? Is there better way to achieve it?

Thanks in advance,

====expected report format======= 

IP         Write/Read TotalTransferData FileName

172.22.32.28 W  6736  /export/file1.log
172.22.220.38 W 6737  /export/file2.log

[download]

===raw data================================ 

#
##DATE  IP Write/Read TransferData FileName
#
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4964,/export/file1.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4964,/export/file2.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4963,/export/file2.log
Sun Aug 21 12:08:21 2011,172.22.112.141, W, 9292,1102,/export/home/ano
+ther.file
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 4964,/export/file2.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 2493,/export/file1.log
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 2355,/export/another.log
Sun Aug 21 12:08:21 2011,172.20.220.38, W, 3699,/export/file2.log
Sun Aug 21 12:08:21 2011,172.20.220.146, W, 1996,<?>
Sun Aug 21 12:08:21 2011,172.22.32.28, W, 2776,/export/file1.log

[download]

In reply to aggregate data by roadtest

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