How to manage HDDs at iVMS 4200 Storage Server?

I connected two partitions (HDDs in Hikvision terminology) to iVMS 4200 Storage Server (please see the pic).

I had 100Gb partition and then added 4Tb one, but the depth of recording didn't increase. I have a suspicion that 4Tb partition is not used.

1) How to see how many minus or MBs are actually stored on each of them?
2) How to delete one of them - the 100Gb one?

When I installed the iVMS-4200 client and storage server, the storage server does not show up. The Storage Server is running with the watchdog in the systray. I have an SSD for the Win10 OS, SSD for clips, and a 3TB iSCSI drive for recording.