First off, one thing I learned was that CoreOS tried adopting BTRFS last year, and too many people tried it, and found issues (like ‘out of space’ when there’s only 30% used in df). CoreOS has since switched to OverlayFS, a union filesystem that runs on top of two EXT4 filesystems. So cool, and it solves my issue of filesystem compatibility, since it makes LVM available. Everything is compatible with EXT4 file systems.
Okay, CoreOS. CoreOS Linux is a new-ish distro, which was originally designed to run Docker containers, but has since defined their own, open source, container image format, rkt. rkt is more flexible than Docker, making Enterprise solutions much easier. CoreOS is designed to be deployed to bare metal (or any hypervisor you like – Amazon, Google, Microsoft – pick your cloud), and join your cluster instantly. The more I learn about CoreOS and fleet, the more I want to run a cluster myself.
CoreOS only supports x86_64, so no Raspberry Pi 2 cluster without cross compiling everything, which is possible, but a royal pain in the arse. LXC works fine, though, so Ubuntu 14.04 LTS on Pi 2 is totally doable.
LXC development is being actively funded by Ubuntu’s Cananical, and seems to be trying to compete with CoreOS, running Docker containers as easily as creating any custom machine you like.
LXC also supports overlayfs, so you can base a number of containers off a read-only version of your favorite version of rootfs as the “lower” filesystem, and each with it’s own writable “upper” LVM based filesystem on top.
CoreOS seems like what we might use at work, if we were a modern company, I mean. I want to know more, I wish I could influence our future somehow, but oh well. I’m sure we’ll get on board in another 5-10 years.
Ubuntu Linux and LXC is what I want to use on my small office/home office server right now.