Fix WAL size
Fix WAL size

This patch fixes the calculation of the size of the WAL in bytes.

Change-Id: Ibdb19c30cec01a5c704f337e69eb51d08f25ed9a

stackforge/fuel-plugin-influxdb-grafana,stackforge/fuel-plugin-influxdb-grafana,stackforge/fuel-plugin-influxdb-grafana,stackforge/fuel-plugin-influxdb-grafana