Bcache Tuneables

The "embedded" configuration file for the bcache devices is as seen below:

{ 
    "tuneables": [
        { "name": "cache_mode", "value": "writeback" },
        { "name": "writeback_percent", "value": "40" },
        { "name": "congested_write_threshold_us", "value": "0" },
        { "name": "congested_read_threshold_us", "value": "0" },
        { "name": "sequential_cutoff", "value": "0" }
    ]
}

These values can be overridden by creating a file named:

/var/run/cluster-control/facts/storage/bcache-config.json

Within this file, add your custom variables in the format shown above.