This DisplayString reports the total disk capacity of the appliance, per 'Disk total space.' It's the fixed denominator against which diskFreeTotal and diskPercent are measured, and it's what an admin uses to judge whether the appliance's storage was ever adequately sized for its logging retention requirements in the first place. A diskTotal far smaller than what current log volume and retention policy require would indicate an under-provisioned appliance rather than a recent usage spike.