Virtual machines

  • VMs are run on Linux KVM hypervisors.

  • The guest operating system is a 32-bit Gentoo Linux managed by the Flying Circus.

    • Packages are installed through the managed components. If you require something special you are free to compile it in your service users’ home.
    • We are always looking for more components to manage for you but as a general rule new managed components take their time to develop them. Contact our support if you would like to make a wish.
  • VMs can be assigned resources:

    • 1-8 CPUs
    • 256MiB-60GiB RAM (note the 32-bit per process memory limit of 3GiB)
    • 5GiB-10+TiB disk (note that filesystems become unwieldy at a certain size)
  • Resources can be resized:

    • CPU and RAM changes currently require a reboot of the VM.
    • Disks can be increased on the fly without a reboot. Disk decreases require a reboot.
  • Virtual disks are stored in CEPH RBD volumes.


For every project maintenance is by default configured between 22:00 and 5:00 with a pre-announcement period of 24 hours. When our tools notice that maintenance is required they will automatically pick a window matching the configured limits and notify the technical contacts.


Automated reboots are announced according the maintenance guidlines. Users granted with sudo-srv permissions are able to reboot a VM by calling:

sudo shutdown -r now