Later versions of Sybase include a monitoring view named monDeviceSpaceUsage that can help us monitor disk space within DPA. This monitoring view shows data for each file for all databases, but we can use some MIN and MAX logic to break that down to the drive level. The query will return multiple rows of free space percentages at the drive level.
To create the alert within DPA, create an alert of type Custom - Custom SQL Alert - Multiple Numeric Alert and configure thresholds accordingly. Note that the lower the free space is, the higher level of alert should be triggered, so use ascending thresholds: