A simple how to for graphing iostats. The output of iostat is useful but its also nice if you can get it into a graph. The idea of this small repository is to show how this is done.

Acknoledgements to the following links where I drew inspiration:

http://www.linuxuser.co.uk/tutorials/create-a-graph-of-your-systems-performance

http://sysmagazine.com/posts/165855/

Theres nothing more special here than a bunch of shell scripts that run gnuplot and could probably be very easily improved. There's a few things that will need to be setup beforehand though and you'll also need to run a iostat command to collect data. Note this was all tested on Centos Linux, you may run into problems running these scripts on a Mac. It's definitely not going to work on MS Windows, sorry!

Also a lot of the scripts are grouped by the type of measurement, i.e. queue length is in requests but queue size is in sectors. Otehr things like read/write requests are per second. I kept all the scripts seperate for now to keep things simpler to follow if for example you only wanted to graph one of two stats.

You'll need to install the following:

• gnuplot
• iostat (usually installed on more common Linux distros)

If you're running this on a MAC you'll need to install homebrew first:

Install brew

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Install GNU Plot

brew install gnuplot

Run the following iostat command for a decent period of time to collect some data:

iostat -xk -t 5 | awk '// {print strftime("%Y-%m-%d %H:%M:%S"),$0}' > iostat-server1.out

You should see a resulting output something like so:

2015-10-29 17:20:18 10/29/2015 05:20:18 PM
2015-10-29 17:20:18 avg-cpu:  %user   %nice %system %iowait  %steal   %idle
2015-10-29 17:20:18            0.96    0.00    2.65    0.00    0.00   96.38
2015-10-29 17:20:18
2015-10-29 17:20:18 Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
2015-10-29 17:20:18 sda               0.00     1.80    0.00    2.00     0.00    12.80    12.80     0.00    0.00   0.00   0.00
2015-10-29 17:20:18 sdb               0.00     0.40    0.00    0.60     0.00     3.20    10.67     0.00    0.00   0.00   0.00
2015-10-29 17:20:18 sdc               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00

In the above output it might be useful to grab all the devices. Here's a useful one-liner you can use for that:

sed -n "/sda/,/sdc/p" iostat-server1.out | cut -d\  -f3 | sort -u > disks

Where "sda" and "sdc" are the first and last disks in your iostat output respectively. Change those for your own needs. You can also redirect the output to a file as shown.

This is the fun part, using the disk-report.sh script, you can then essentially loop through all the disks and then produce the output. For example

/disk-report.sh discs iostat-server1.out

Note you might see some warnings on fonts but you shouldnt see any errors

This will create a bunch of .png files which you can then view with your favourite image viewer and / or embed into presentations to impress your audiences :-)