The allocated space of a tablespace is the sum of the current size of its datafiles. Some of this allocated space is used to store data and some of it may be free space. If segments are added to a tablespace, or if existing segments grow, they will use the allocated free space. The allocated free space is only available to segments within the tablespace. If, over time, the segments within a tablespace are not using this free space, then the allocated free space is being wasted.
This metric calculates the space used for each tablespace. It is not intended to generate alerts. Rather it should be used in conjunction with the Tablespace Allocated Space (MB) metric to produce an historical view of the amount of space being used and unused by each tablespace.
The rest of the information in this section is only valid for this metric when it appears in either the Enterprise Manager Grid Control or the Enterprise Manager Database Control (if applicable).
The following table shows how often the metric's value is collected.
Every 7 Hours
Tablespace Used Space (MB) is Tablespace Allocated Space (MB) – Tablespace Allocated Free Space (MB) where:
Tablespace Allocated Space (MB) is calculated by looping through the tablespace’s data files and totaling the size of the data files.
Tablespace Allocated Free Space (MB) is calculated by looping through the tablespace’s data files and totaling the size of the free space in each data file.
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