Back to basics.
If you manually roll over partitions, you need to monitor the storage used by the partition. If you roll over per time-slot (month/year), then also keep an eye on storage ;-). It might go faster than you think. To be able to roll over, you need a READY partition. At the time where you set that READY to OPEN, EV will automatically set the old partition to CLOSED. If you have expiry running (and thus create space on closed partitions), you might be able to re-use the old partitions again. If you want to re-use, set it to Ready. You can then either set the roll-over to ocurr automatic (based on free space/age), or do it manually.