Support block.wal in not-PVC deployment

[chenyuanrun]

Rook seems support block.wal only if the osd is running under PVC, It would be better if we can use block.wal for high speed devices in host.

Is this a bug report or feature request?

• Feature Request

What should the feature do:

What is use case behind this feature:

Environment:

[travisn]

Have you tried with the metadataDevice setting? This

  storage:
    config:
      metadataDevice: nvme01

The config section can also be under the nodes, like this:

  storage:
    nodes:
    - name: node1
      config:
        metadataDevice: nvme01

This will pass the device to the ceph-volume arg --db-devices. IIRC ceph will also put the wal on this metadata device as well. But if you really want the wal on a separate device, you're correct I don't see that option. @satoru-takeuchi Is that correct?

[satoru-takeuchi]

@travisn Yes, metadataDevice should work.

https://rook.io/docs/rook/latest-release/CRDs/Cluster/ceph-cluster-crd/#osd-configuration-settings

[chenyuanrun]

@travisn Yes I mean use a separate device for wal, I have checked the code of rook and I confirm that rook support only ONE metadata device for both db and wal for non-PVC disk, but if you use PVC for osd, you can use separate wal device.