I am currently using threshold triggers to alert when disk free space drops below a certain percent. However, I would prefer to alert based on the rate of consumption. For example, a drive has been at 11% free for 6 months and has change to 10%, causing an alert. If the system stays true to form, I can expect the drive to sit at 10% for months. Under these circumstances the alert is effectively useless. Now, let's say the drive hit a warning alert at 25% free and 1 minute later hits an error at 10% free, with a system crash a minute later due to loss of space. Is there a way to alert based on the change of percent of bytes between scans? So if there is a 1% change in free space, nothing happens, but if there is a 15% change in space, for example, I can receive an alert.