Graphviz for lab configuration visualization

Setting up my lab environment for testing can be messy and confusing. I’m not just talking about the cable mess, but also how my 8 initiator systems are going to connect to my 2 target systems so that they’ve each got multiple paths. Different multipath options affect the resulting performance numbers, so it’s important to have the multiple paths.

To help me visualize how I was going to have to address my NICs (for a 40Gb/s iSCSI test) for an even distribution between my initiators, I started by drawing it out on paper. But that’s not very good for documenting my configuration for the test library archive. So I looked into more portable options and found Graphviz. This isn’t an obscure piece of software, I’ve seen it mentioned around, but I didn’t know how easy it is to get started using it. I don’t really run any Linux systems with a GUI but it’s available on my Mac via Homebrew.

A pretty simple .dot file like this:

graph iscsi {
// $ dot -Tpng iscsi.dot -o iscsi.png
  graph [pad=".75", ranksep="5.50", nodesep="0.25"];
  node [shape=box]
  rankdir = LR

  subgraph cluster_t5 {
    label = "t5";
    target51 [label="eth2"]
    target52 [label="eth4"]
    target53 [label="eth6"]
    target54 [label="eth7"]
  }
  subgraph cluster_t6 {
    label = "t6";
    target61 [label="eth2"]
    target62 [label="eth4"]
    target63 [label="eth6"]
    target64 [label="eth7"]
  }

  n10 -- target51 [label="192.168.11.x"]
  n10 -- target52 [label="192.168.13.x"]
  n10 -- target61 [label="192.168.11.x"]
  n10 -- target62 [label="192.168.13.x"]
  n11 -- target53 [label="192.168.12.x"]
  n11 -- target54 [label="192.168.14.x"]
  n11 -- target63 [label="192.168.12.x"]
  n11 -- target64 [label="192.168.14.x"]
  n12 -- target51 [label="192.168.11.x"]
  n12 -- target52 [label="192.168.13.x"]
  n12 -- target61 [label="192.168.11.x"]
  n12 -- target62 [label="192.168.13.x"]
  n13 -- target53 [label="192.168.12.x"]
  n13 -- target54 [label="192.168.14.x"]
  n13 -- target63 [label="192.168.12.x"]
  n13 -- target64 [label="192.168.14.x"]
  n14 -- target51 [label="192.168.11.x"]
  n14 -- target52 [label="192.168.13.x"]
  n14 -- target61 [label="192.168.11.x"]
  n14 -- target62 [label="192.168.13.x"]
  n15 -- target53 [label="192.168.12.x"]
  n15 -- target54 [label="192.168.14.x"]
  n15 -- target63 [label="192.168.12.x"]
  n15 -- target64 [label="192.168.14.x"]
  n16 -- target51 [label="192.168.11.x"]
  n16 -- target52 [label="192.168.13.x"]
  n16 -- target61 [label="192.168.11.x"]
  n16 -- target62 [label="192.168.13.x"]
  n17 -- target53 [label="192.168.12.x"]
  n17 -- target54 [label="192.168.14.x"]
  n17 -- target63 [label="192.168.12.x"]
  n17 -- target64 [label="192.168.14.x"]

}

Produces a graph like this:

All with a simple command, in this case: $ dot -Tpng iscsi.dot -o iscsi.png

It’s much more flexible than that, but the one thing I wish it had was output to ascii. Graph-Easy has ascii output, even from the Graphviz .dot files, but the rendering isn’t too great in my testing.