This section describes the design considerations for status files.
In order to provide a safety margin until a disk becomes operational after it has been recovered from a disk failure, we recommend that you provide six sets of status files on four sets of disks (dual files x 6 = 12 files) and place them as shown in the following figure. If an error occurs on the normal system during single operation, HiRDB cannot be restarted; therefore, we recommend that you do not apply single operation to status files (specify stop in pd_syssts_singleoperation and pd_sts_singleoperation).
The following figure shows an example of placing six sets of status files on four sets of disks.
Figure 8-4 Example of placing six sets of status files on four sets of disks
The pd_syssts_file_name_1 to pd_syssts_file_name_7 and the pd_sts_file_name_1 to pd_sts_file_name_7 operands are used to define the correspondence between the status files created by the pdstsinit command and the logical files.
The pd_syssts_file_name_1 to pd_syssts_file_name_7 operands are for unit status files, and the pd_sts_file_name_1 to pd_sts_file_name_7 operands are for server status files.
If the names of imaginary logical files or status files are defined in the pd_syssts_file_name2 to pd_syssts_file_name7 operands or in the pd_sts_file_name2 to pd_sts_file_name7 operands, status files can be added during HiRDB operation. In such a case, the following operands must be specified.
pd_syssts_initial_error
pd_syssts_last_active_file
pd_sts_initial_error
pd_sts_last_active_file
If an error occurs on one of the current files while there is no available spare file, continuing operation using only the normal file (either the primary or secondary file) is called status-file single operation. When status files are placed in the single operation mode, the KFPS01044-I message is displayed.
If an error occurs on the current file in the single operation mode, HiRDB can no longer be restarted. Therefore, status-file single operation is not recommended. Increase the number of status file sets to avoid a situation where no spare file is available.
As opposed to status-file single operation, continuing operation using both status files (normal processing mode) is called status-file double operation.
To use unit status-file single operation, specify pd_syssts_singleoperation = continue in the unit control information definition file. To use server status-file single operation, specify pd_sts_singleoperation = continue in the server definition. Make sure that pd_syssts_singleoperation and pd_sts_singleoperation have the same value.
The following are guidelines on when to use status-file single operation.
The following table outlines HiRDB operations and HiRDB administrator actions that depend on whether single operation is used. For details about how to handle status file errors, see the HiRDB Version 9 System Operation Guide.
Table 8-3 HiRDB operation and HiRDB administrator's action that depend on whether single operation is used
Condition | Status-file single operation (pd_syssts_singleoperation or pd_sts_singleoperation operand value) | ||
---|---|---|---|
Used (continue specified) | Not used (omitted or stop specified) | ||
There are spare files | Error occurred in the current file | HiRDB operation: Swaps status files. HiRDB administrator's action: Handle the error in the applicable status file. | |
Error occurred on both current files simultaneously | HiRDB operation: Terminates abnormally. HiRDB cannot be restarted. HiRDB administrator's action: See Handling of status file errors in the HiRDB Version 9 System Operation Guide. | ||
There is no spare file | Error occurred in one of the current files | HiRDB operation: Resumes processing using single operation. HiRDB administrator's action: Create spare files immediately and return HiRDB to the double operation mode. | HiRDB operation: Terminates abnormally. HiRDB administrator's action: Create spare files, and then restart HiRDB. |
Error occurred on both current files simultaneously | HiRDB operation: Terminates abnormally. HiRDB cannot be restarted. HiRDB administrator's action: See Handling of status file errors in the HiRDB Version 9 System Operation Guide. | ||
Error occurred in the normal file during single operation | HiRDB operation: Terminates abnormally. HiRDB cannot be restarted. HiRDB administrator's action: See Handling of status file errors in the HiRDB Version 9 System Operation Guide. | -- |