gnuplot_acquire.pl

#!/usr/bin/perl -w

use strict;
use warnings;

use POSIX;

sub main {
  if(@ARGV < 3) {
    die "Usage: $0 pattern seconds output";
  }
  
  my $ph;
  open $ph, "iostat -d -x 2 |";
  
  my $filename =  $ARGV[2];
  my $fh;
  open $fh, ">$filename" or die "open(): $!";
  
  my $pattern = quotemeta $ARGV[0];
  my $seconds = $ARGV[1];
  
  my $start_time = time();
  
  while(my $line = <$ph>) {
    my $current_time = time();
    if($line =~ /$pattern/) {
      print {$fh} strftime("%d-%m %k:%M:%S", localtime($current_time)) . " $line"; 
    }
    if(($current_time - $start_time) > $seconds) {
      clean_up($fh, $ph);
      exit 0;
    }
  }
  
  clean_up();
}

sub clean_up {
  my @handles = @_;

  foreach my $handle(@handles) {
    eval {
      close $handle;
    };
    if($@) {
      print "close(): $@";
    }
  }
}

&main;

plot

#!/usr/bin/gnuplot
set terminal png
set output "disk.png"
set title "Disk Activity"
set xdata time
set xlabel "time"
set ylabel "IOPS"
set timefmt "%d-%m %H:%M:%S"
set format x "%H:%M"
plot "iostat.out" using 1:4 title "reads" with lines, \
"iostat.out" using 1:5 title "writes" with lines