Stacked Histograms in gnuplot

I like to graph things out a lot. In some cases the actual values of the graph don't matter for the most part. I just need a quick view of a system that has been graphed to see if it's normal or not. Specifically in this case, I was looking for an evenly distributed load on some servers.

I chose a stacked histogram because it was easier to see distribution compared to something like a line chart. Likewise it needed to be stacked due to such a large set of data per polling interval. It took a bit of playing around but I finally got it to work how I wanted.


set term png
set output '/var/www/Graph.png'
set terminal png size 1500,400
set boxwidth 0.75 absolute
set style fill solid 1.00 border lt -1
set key outside # < I ended up doing an unset key later due to the size
set style histogram rowstacked
set style data histograms
set xtics norangelimit font ",8"
set xtics rotate by 270
set xlabel "  "
set autoscale
set grid
# The source file has many sections of data for other charts. This histogram was for 32-83 (1 was the time %H:%M). Server names removed.
plot 'gnuplotdata.dat' using 32:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 33:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 34:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 35:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 36:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 37:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 38:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 39:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 40:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 41:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 42:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 43:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 44:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 45:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 46:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 47:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 48:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 49:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 50:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 51:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 52:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 53:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 54:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 55:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 56:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 57:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 58:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 59:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 60:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 61:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 62:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 63:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 64:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 65:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 66:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 67:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 68:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 69:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 70:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 71:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 72:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 73:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 74:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 75:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 76:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 77:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 78:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 79:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 80:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 81:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 82:xtic(1) title 'serverX', \
'gnuplotdata.dat' using 83:xtic(1) title 'serverX'


You can't really use a key with this due to the large data set making many of the colors too similar. I decided to 'unset key' after the key was taking up half the image. Again, this wasn't for an exact reference. This was so I could glance and see something was wrong and then go to my not so friendly data file and see what server had what issue. So the below was the chart showing a pretty evenly distributed load. The 'load' itself constantly changes and there is no baseline or reference point due to the nature of the load. So the only reference they have is to each other. Yes there are simpler ways to determine if they are loaded nearly the same all around, but that's not as cool.