Starting from the cloud control 12c The Space Summary Page section was removed as the page design was changed.
The Space Summary section was displaying the following informations like:
a) Database Size (GB)
b) Problem Tablespaces
c) Segment Advisor Recommendations
d) Space Violations
e) Dump Area Used (%)
Now the same informations are split in categories and can be found under the following options:
- Performance menu->Advisor home
- Monitoring->All metrics
Regarding second query on how to monitor tablespace usage from all database instance targets you can review the below information
These are OOB 12c reports.
-- Oracle Database Space Usage (Group)
[Displays space usage and tablespace full alerts for each Oracle Database in a group.]
-- Oracle Database Tablespace Daily Space Usage
[Displays space usage for an Oracle Database, its tablespaces and datafiles.]
-- Oracle Database Tablespace Monthly Space Usage
[Displays monthly space usage details for the tablespaces in an Oracle Database.]
To create customized reports according to your requirements you have to write your own sql based on the following views.
All the required data would be in the following.
mgmt_metrics , mgmt_current_metrics , mgmt_targets
Also you can explore the option of creating Report Based On A Metric Extension
EM12c: How To Create A Custom Report Based On A Metric Extension in Enterprise Manager 12c Cloud Control (Doc ID 1622443.1)
How to create a Customized Report in 12c Cloud Control for Database Alert log Errors (Doc ID 1528268.1)