Speaking of sandboxes, I was making some quick tests yesterday, and I installed 15 sandboxes at once (all different versions, from 5.0.91 to 5.6.5). Installing a single sandbox, depending on the version, takes from 5 to 19 seconds. Do you know how long it takes to install 15 sandboxes, completely, from tarball to working conditions? It takes 19 seconds. How's so? It's because I have been working at a large project where we are dealing with many replicated clusters spread across three continents. Administering these clusters is a problem in itself, and so we are using tools to do our work in parallel. At the same time, using a host with a fast 16 core CPU I can install many sandboxes at once. It's a real joy to see software behaving efficiently the way it should! It works so fast, in fact, that I found a race condition bug. If you install more than one sandbox at once, the MySQL bootstrap process may try to open the same temporary file from two different servers. That's because I did not indicate a dedicated temporary directory for the bootstrap (I was using one only for the installed sandbox). When this happens, you may find that instead of 15 sandboxes you have installed only 9 or 11. So I fixed the bug, by adding --tmpdir to mysql_install_db, and now you can install more than one sandbox in parallel.