Disk space = base, change in disk space = 1st derivative, rate of change = 2nd derivative. Useful as a monitor for the rate of change in data intensive applica

Disk space = base, change in disk space = 1st derivative, rate of change = 2nd derivative. Useful as a monitor for the rate of change in data intensive applications that sometimes spill to disk. Spikiness is okay if it reverts towards the base within a certain timeframe, but not okay if the rate of change persists or increases over same timeframe.