Quantification
The following values are reported.
| Under Heading | This is Displayed |
|---|---|
| Type | DATA or INDEX. This indicates if the buffers are for VSAM DATA or INDEX components |
| Buffer Size | The buffer size, in bytes. |
| Buffers | The number of buffers in virtual storage. |
| Hiperspace™ Buffers | The number of buffers in Hiperspace. |
| Reads | The number of physical reads to the file. This is the number of reads that could not be avoided because no buffer contained a copy of the CI. Three values are shown: “Initial,” which is the value at the start of the measurement interval; “Last,” which is the value at the end; and “Difference,” which is the difference between the other two values. The difference between the two values represents the activity for the duration of the interval. |
| Reads Avoided | The number of avoided reads (look-asides). This is the number of reads avoided because copies of the referenced CIs were found in the buffer pool. Three values are shown: “Initial,” which is the value at the start of the measurement interval; “Last,” which is the value at the end; and “Difference,” which is the difference between the other two values. The difference between the two values represents the activity for the duration of the interval. High values indicate the buffer pool was effective in causing I/O operations to be avoided. |
| User Writes | The number of physical writes performed to the file at the request of the user program. Three values are shown: “Initial,” which is the value at the start of the measurement interval; “Last,” which is the value at the end; and “Difference,” which is the difference between the other two values. The difference between the two values represents the activity for the duration of the interval. |
| Non-user Writes | The number of forced physical writes performed to the file. Three values are shown: “Initial,” which is the value at the start of the measurement interval; “Last,” which is the value at the end; and “Difference,” which is the difference between the other two values. The difference between the two values represents the activity for the duration of the interval. |