ZFS Powered Magic Upgrades

Allan Jude <allanjude@freebsd.org>

Using boot environments for atomic in-place upgrades

Describe a system of using ZFS Boot Environments to quickly, safely, and atomically upgrade 100s of remote machines.


  • How the file system hierarchy is modified to allow the systems to be upgraded in-place
  • How we use ZFS to create and deploy the boot environments
  • Simplifying the creation of the BEs using poudriere image
  • Extending poudriere image to support ZFS
  • Using zfsbootcfg to boot a new BE once
  • How we determine if the BE “works” and should be promoted to the default


  • We often have only SSH access to the machines, so we needed something that could self-recover just by power cycling the machine
  • No longer need to use freebsd-update, mergemaster, or etcupdate