The file header contains fields that GT.M uses in the Buffered Global (BG) access method. These fields should NOT be modified using DSE, except under the guidance of Fidelity Information Services.
The file header control fields are:
|
Data Element |
Description |
|
Access method |
Either Mapped Memory (MM) or Buffered Globals (BG); original value taken from Global Directory; modified with MUPIP SET. |
|
Cache freeze |
Used by MUPIP to suspend updates during BACKUP, FREEZE, INTEG, and optionally during EXTRACT; directly manipulated with MUPIP FREEZE. |
|
Flush timer |
OpenVMS delta time indicating the time processes wait after a database update before initiating a flush. |
|
Flush trigger |
Number of modified that cause the next updating process to initiate a flush. |
|
Global buffers |
Number of central cache records; original value taken from Global Directory; modified with MUPIP SET. |
|
Last comp backup |
Transaction number of last comprehensive backup. |
|
Last inc backup |
Transaction number of last incremental backup. |
|
Last rec backup |
Transaction number of last MUPIP BACKUP /RECORD or FREEZE /RECORD |
|
No. of writes/flush |
Number of blocks to write in each flush. |
|
Timers pending |
Number of processes considering a timed flush. |
In addition to the control fields, GDS files also reserve room for a pool of cache buffers in the file header.