Ignition & storage allocation

I’d like to use Fedora CoreOS on my servers (bare metal) who all have different storage setup.

My goal is to implement the following:

  • / is installed on sda (always available on all nodes)
  • /var uses all /dev/nvme* devices in a raid0 or lvm stripe mode (at least one nvme drive is available per node)

My understanding is that this is not supported today, but I’m rediscovering CoreOS after a few years, and trying on bare metal for the first time :wink:
I am looking for guidance/input if anyone tried something along those lines.

This is what I did as a workaround:

Create an ignition file that provisions a /var filesystem with /dev/nvme0n1 only on btrfs, provision my nodes and script add all the other devices with btrfs device add and a balance operation to adjust the raid settings.

That works and should be fine with the upgrades since /var is not touched.

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We have an example of how to do RAID in our docs but IIUC that doesn’t use the BTRFS builtin RAID capabilities, but rather mdraid.

What you came up with seems like a reasonable resolution for now.