In the beginning, users time-shared CPUs and virtualization was without form and void. And IBM said “Let there be System/370”. This was in the 70’s and involved men with crew-cuts, horn-rimmed glasses and pocket protectors. And ties.

Today, you can still do full virtualization. Everything is emulated down to the hardware and every system has it’s own kernel and device drivers. Most of the public cloud started out this way at the dawn of the new millennium. It was the way. VMWare was the early player in this area and popularized it on x86 hardware where everyone was using 5% of their pizzabox servers.

The newer way is containerization. There is just one kernel and it keeps groups processes separate from each other. This is possible because Linux implemented kernel namespaces around 2008 - mostly work by IBM, suitably enough. The program used to work with this is named LXC and you’d use commands like sudo lxc-create --template download --name u1 --dist ubuntu --release jammy --arch amd64. Other systems such as LXD and Docker (originally) are layed on top to provide more management.

Twenty some years later, what used to be a hot market is now a commodity that’s essentially given away for free. VMWare was acquired by Broadcom who’s focused on the value-extraction phase of it’s lifecycle and the cloud seems decidedly headed toward containers because of it’s better efficiency and agility.

Last modified June 4, 2024: virt overview (f262aea)