5.3.3.2. Using dedicated write-ahead log (WAL) devices

You can specify a dedicated write-ahead log (WAL) device. Using devices, dedicated_devices, and bluestore_wal_devices together means that you can isolate all components of an OSD on to separate devices, which can increase performance.

In the following example procedure, another additional dictionary, bluestore_wal_devices, isolates the write-ahead log on NVMe devices nvme0n1 and nvme0n2.

Procedure

  1. Add the following content to an environment file:

    parameter_defaults:
      CephAnsibleDisksConfig:
        devices:
          - /dev/sda
          - /dev/sdb
        dedicated_devices:
          - /dev/sdx
          - /dev/sdy
        bluestore_wal_devices:
          - /dev/nvme0n1
          - /dev/nvme0n2
  2. Include the environment file that contains your new content in the deployment command with the -e option when you deploy the overcloud.