EV server losing disk space on drives with closed partitions

I am running EV 10.0.0.1090 with Exchange Server 2007

I am running out of disk space on drives that contain only closed partitions. Both drives, K: and M: were left with 50 GB of free disk space. The last partition on M: was closed in September and the last Partition on K: was closed in 2013. In the past couple of weeks, both of these drives have had their free disk space go down to 0, impacting EV performance. When I run collections on the partitions on both of these drives, I recover disk space. What is EV doing to eat up the disk space on these drives and why are there still files that can be collected?

I have attached a screen shot of the drives and the partitions

thank you