| Measurement |
Description |
Measurement
Unit |
Interpretation |
| Usable_size |
The data area that is currently available for data |
MB
|
There must also always be sufficient space in the data area to hold all the data that is created during database operations. Therefore, ideally, this value should be high.
|
| Used_size |
The memory in data area that is currently used for data |
MB
|
|
| Pct_used_size |
The percentage of memory in the data area that is actually used for data |
Percent
|
Ideally, this value should not be very high.
|
| Data_on_volume |
The amount of data that has been written to the data area, currently |
MB
|
|
| Data_not_on_volume |
The amount of permanent data that has to be written to the data area at the next savepoint
|
MB
|
Pagers (which are tasks in the user kernel thread) write the data from the data cache to the data area for each savepoint. If a lot of data was changed and the pagers would have to write many pages at the next savepoint, then the pagers write data from the data cache to the data area before the next savepoint.
|
| Permanent_size_used |
The data area that is currently used for permanent data
|
MB
|
|
| Temporary_size_used |
The data area that is currently used for temporary data
|
MB
|
A large proportion of temporary data indicates large amounts of (buffer) result sets. If the value of this measure is high, then find the statement that is causing large amounts of (buffer) result sets to be created, and check the access strategies for this statement.
|