I have just set up a bunch of VMs at home and am looking for some interesting things to play around with. I was just wondering what kind of random stuff can one experiment with with such a set up? I'm not looking to set up stand-alone servers but I am thinking of experimenting with inter-machine stuff.
As an example, I have got a single VM exposed to the outside world with a reverse proxy running on it that points to other VMs. Also, all these VMs are running Debian and I have one VM running as a local apt cache to the rest of the VMs.
Are there some sort of distributed or cluster or some other interesting thing to play with? VMs are supposed to be fun!
Learn Erlang, Clojure, Scala, or some other language that's aimed at distributed, reliable systems.
Try setting up a high availability cluster for various services. Basically, follow the guides on linux-ha.org to set up DRBD, Heartbeat, STONITH, etc.
Either way, take advantage of your VMs to actually torture test the setups. Pull VMs offline and bring them back and see what happens. Do your worst to try to get yourself into a split-brain situation. See if you can figure out how to fix it. See what happens (ie, what kinds of errors occur) if more nodes go offline than your setup is supposed to be able to handle.