Can I create partition on OS disk in fedora coreos

Hi Team,

I am newbie to fedora coreos, just have two queries.

  1. Is it possible to create partition on OS disk in fedora coreos (like normal Linux) with ignition file? I tried it, but every time it fails with error inappropriate ioctl with device. If it is possible, please point me to some documentation link.

  2. Is it possible to write fedora coreos on two disk in raid 1 configuration. I have two disk on server can both be used for OS setup in raid 1 configuration

Thanks in advance, It would be great if somebody can point me in right direction.


Amit Bondwal

  1. The Example for adding a /var partition to the primary disk should help you here.
  2. I’m not 100% sure that this is available in a stable release yet, but this is coming. I’ll update this once I have a better answer.

Hi @Siosm, Thanks for your reply. I tried a lot of options, I not able to get it run after reboot while creating partition on the OS disk.

Please find my ignition yml file on pastebin

I tried disk name with /dev/sda as well with /dev/disk/by-id/xxxx. Result was always same.

What wrong, I am doing in this.


Amit Bondwal

To add a partition to an existing disk, you don’t want to wipe and recreate all partitions (that will not work as all content will be lost) but instead keep the existing one and only add the one you want. See this example:

variant: fcos
version: 1.1.0
    # The name of the primary block device. In virtio-based setups, this is
    # likely `/dev/vda`. Elsewhere, it's likely `/dev/sda`.
    device: /dev/vda
    # We do not want to wipe the partition table since this is the primary
    # device.
    wipe_table: false
    - size_mib: 0
      # Start at 5G so that we leave enough space for the root partition.
      start_mib: 5000
      # We assign a descriptive label to the partition. This is important
      # for referring to it in a device-agnostic way in other parts of the
      # configuration.
      label: var
    - path: /var
      device: /dev/disk/by-partlabel/var
      format: xfs
      with_mount_unit: true

For your second question, RAID 1 support for root is coming in the next stable release which should be available next week. In the meantime you can test this with testing and the example in this docs PR:

Hi @Siosm, Thank you very much for this detailed reply. It worked like charm. I was thinking, it should work like a normal linux, in case of partition. But I am surprised to see this way, it is working. Even documentation not saying anything about this, how it works.

I will test the raid 1 too with testing iso soon.

So what I understand, we can’t change in main partitions manually like sysroot, boot, boot/efi. It should be as it is, it took space automatically, what is left.

It would be great help, if you could share some documentation link from which I could learn more of internals (basically to do thing manually to understand better fedora coreos). What are difference between normal linux and fedora coreos (in case of internal usability)

I will update you once I am done with raid1 testing too. Thanks again.


Amit Bondwal

There is an in-progress PR to explain that:
In short, you can only use separated partitions for /var and all sub directories. “Everything else” is managed by rpm-ostree.