I will always look back on Solaris wistfully. It was (and will always be) my favorite Unix. When containers showed up... oh man... my lab guys lost their mind. We had a never ending parade of upgrades...and server rotation. Enter zones... and things just become OOM easier. Want a zone of your own? No prob. Wonderful isolation and resource allocation, too. The network stack was a bit iffy in the early days, but Sun sorted it out. All our zones (incl. root!) were on NAS... we could move zones around the hardware at will. It was incredibly useful and a whole lot of fun.