Thanks a lot for your excellent idea abouot using Conditional Operator....

#!/usr/bin/env perl
use strict; use warnings;

my %h; my %d; my %ser; my %met;

my $x=0;
while(<DATA>){
    next unless /\w/;
    my($server,$datetime,$metric,$value) = (split)[0,1,2,3];
    $value =~ s/,//g ;
    my $ddhh = substr $datetime,0,13;
    my $dd   = substr $datetime,0,10;
    $d{$dd    }{$server}{$metric}{max} = ($x < $value) ? $value : $x;
    $d{$dd    }{$server}{$metric}{min} = ($x > $value) ? $value : $x ;
    $h{$ddhh  }{$server}{$metric}{max} = ($x < $value) ? $value : $x;
    $h{$ddhh  }{$server}{$metric}{min} = ($x > $value) ? $value : $x ;
    $ser{$server} = 1;
    $met{$metric} = 1;
}

print "Frequency Hour:\ncollectionTime\n\n";

for my $key (sort keys %h){
    print "$key ";
   for my $ser_key (sort keys %ser){
     print "$ser_key  ";
      for my $met_key (sort keys %met){
         print "  $met_key";
         printf " %10s", $h{$key}{$ser_key}{$met_key}{max}; print "  "
+;
         printf " %10s", $h{$key}{$ser_key}{$met_key}{min}; print "  "
+;
      }
   }
 print "\n";
}

__DATA__
server01:         2015-06-23T21:58:05-05:00       FC_IO_BY_R      13,5
+50,785 MB
server01:         2015-06-23T21:58:05-05:00       FC_IO_BY_W      6,89
+2,224 MB
server01:         2015-06-23T21:59:05-05:00       FC_IO_BY_R      13,5
+51,835 MB
server01:         2015-06-23T21:59:05-05:00       FC_IO_BY_W      6,89
+2,339 MB
server01:         2015-06-23T22:00:05-05:00       FC_IO_BY_R      13,5
+52,066 MB
server01:         2015-06-23T22:00:05-05:00       FC_IO_BY_W      6,89
+2,433 MB
server01:         2015-06-23T22:01:05-05:00       FC_IO_BY_R      13,5
+53,303 MB
server01:         2015-06-23T22:01:05-05:00       FC_IO_BY_W      6,89
+2,590 MB
server01:         2015-06-23T22:02:05-05:00       FC_IO_BY_R      13,5
+55,006 MB
server01:         2015-06-23T22:02:05-05:00       FC_IO_BY_W      6,89
+2,836 MB
server01:         2015-06-23T22:03:05-05:00       FC_IO_BY_R      13,5
+56,007 MB
server01:         2015-06-23T22:03:05-05:00       FC_IO_BY_W      6,89
+2,961 MB
server01:         2015-06-23T22:04:05-05:00       FC_IO_BY_R      13,5
+56,201 MB
server01:         2015-06-23T22:04:05-05:00       FC_IO_BY_W      6,89
+3,086 MB
server01:         2015-06-23T22:05:05-05:00       FC_IO_BY_R      13,5
+56,408 MB
server01:         2015-06-23T22:05:05-05:00       FC_IO_BY_W      6,89
+3,208 MB
server02:         2015-06-23T21:58:54-05:00       FC_IO_BY_R      13,4
+70,021 MB
server02:         2015-06-23T21:58:54-05:00       FC_IO_BY_W      7,43
+1,544 MB
server02:         2015-06-23T21:59:54-05:00       FC_IO_BY_R      13,4
+70,381 MB
server02:         2015-06-23T21:59:54-05:00       FC_IO_BY_W      7,43
+1,642 MB
server02:         2015-06-23T22:00:54-05:00       FC_IO_BY_R      13,4
+71,003 MB
server02:         2015-06-23T22:00:54-05:00       FC_IO_BY_W      7,43
+1,760 MB
server02:         2015-06-23T22:01:54-05:00       FC_IO_BY_R      13,4
+71,334 MB
server02:         2015-06-23T22:01:54-05:00       FC_IO_BY_W      7,43
+1,980 MB
server02:         2015-06-23T22:02:54-05:00       FC_IO_BY_R      13,4
+71,629 MB
server02:         2015-06-23T22:02:54-05:00       FC_IO_BY_W      7,43
+2,196 MB
server02:         2015-06-23T22:03:54-05:00       FC_IO_BY_R      13,4
+71,947 MB
server02:         2015-06-23T22:03:54-05:00       FC_IO_BY_W      7,43
+2,307 MB
server02:         2015-06-23T22:04:54-05:00       FC_IO_BY_R      13,4
+72,575 MB
server02:         2015-06-23T22:04:54-05:00       FC_IO_BY_W      7,43
+2,418 MB
server02:         2015-06-23T22:05:54-05:00       FC_IO_BY_R      13,4
+73,473 MB
server02:         2015-06-23T22:05:54-05:00       FC_IO_BY_W      7,43
+2,586 MB
[download]

Maximum values are fine, but as you said I am struck with Minimum values defined, its always getting initialized to 0.

Could you please help me to come out of it? I mean, is there any way to initialize the actual minimum values?

You were using the same variable $x for max and min, and never updating it, nor comparing with the current max value for a $server and $metric combination. I'm surprised either max or min was correct. I suggest an alternative approach.

while(<DATA>){
    next unless /\w/;
    my($server,$datetime,$metric,$value) = (split)[0,1,2,3];
    $value =~ s/,//g ;
    my $ddhh = substr $datetime,0,13;
    my $dd   = substr $datetime,0,10;
    if (! defined($d{$dd    }{$server}{$metric}{max})) {
      $d{$dd    }{$server}{$metric}{max} = 0; 
      $d{$dd    }{$server}{$metric}{min} = 99999999;
      $h{$ddhh  }{$server}{$metric}{max} = 0;
      $h{$ddhh  }{$server}{$metric}{min} = 99999999;
    }
    $d{$dd    }{$server}{$metric}{max} = $value if ($d{$dd    }{$serve
+r}{$metric}{max} < $value);
    $d{$dd    }{$server}{$metric}{min} = $value if ($d{$dd    }{$serve
+r}{$metric}{min} > $value);
    $h{$ddhh  }{$server}{$metric}{max} = $value if ($h{$ddhh  }{$serve
+r}{$metric}{max} < $value);
    $h{$ddhh  }{$server}{$metric}{min} = $value if ($h{$ddhh  }{$serve
+r}{$metric}{min} > $value);
    $ser{$server} = 1;
    $met{$metric} = 1;
}
[download]

Dum Spiro Spero

See defined or exists.

--MidLifeXis

Confused...My previous code just traverse till the end of DATA and just displays the end data. Its not performing what I am willing to do.

my $x=0;
while(<DATA>){
    next unless /\w/;
    my($server,$datetime,$metric,$value) = (split)[0,1,2,3];
    $value =~ s/,//g ;
    my $ddhh = substr $datetime,0,13;
    my $dd   = substr $datetime,0,10;
    $d{$dd    }{$server}{$metric}{max} = ($x < $value) ? $value : $x;
    $d{$dd    }{$server}{$metric}{min} = ($x > $value) ? $value : $x ;
    $h{$ddhh  }{$server}{$metric}{max} = ($x < $value) ? $value : $x;
    $h{$ddhh  }{$server}{$metric}{min} = ($x > $value) ? $value : $x ;
    $ser{$server} = 1;
    $met{$metric} = 1;
}
[download]

In above code $x < $value always holds true and just traverse till end of DATA...it doesn't find the maximum value. If you don't mind can you please provide me the pseudo-code OR any hints to achieve it?