When the standby system switchover facility is used, the statistics log files consist of the two files pdstj1 and pdstj2. These files are created automatically for both the primary system and the secondary system, so the HiRDB administrator must prepare a total of four files. Statistics log files cannot be shared between the primary system and the secondary system.
When the standby-less system switchover (1:1) facility or the standby-less system switchover (effects distributed) facility is used, the statistics log files consist of the two files pdstj1 and pdstj2. These files are created as a set for the primary HiRDB system. Because the accepting unit's statistics log files are shared at the switching destination, no files are created for the secondary system. The HiRDB administrator must prepare files for the regular unit and for the accepting unit.
Because statistics log files are distributed to each server machine when system switchover occurs, create unload statistics log files on a specific server machine. Hitachi recommends creating unload statistics log files in the following cases:
Figure 25-70 shows examples of unload statistics log files created when a system switchover facility is used.
Figure 25-70 Examples of unload statistics log files created when a system switchover facility is used (Part 1)
When system switchover occurs, the statistics log files to be used by the switching-destination host are the files being used by the accepting unit at the switching destination. Because statistics log output destination files are distributed to each host, unload statistics log files must be created on a specific server machine.
You should create unload statistics log files at the following times:
Figure 25-71 shows examples of unload statistics log files created when a system switchover facility is used.
Figure 25-71 Examples of unload statistics log files created when a system switchover facility is used (Part 2)
After system switchover occurs, the following operands specify whether or not statistical information is to be collected by the HiRDB on the switchover destination system:
If Y is specified in the pd_statistics operand or the pdstbegin operand is specified, statistical information is collected immediately after system switchover occurs.
If system switchover occurs when the pdstbegin command is being used to start collecting statistical information, HiRDB on the switchover destination system cannot collect statistical information. To collect statistical information in this situation, you must use HiRDB on the switchover destination system to execute the pdstbegin command.
Also, HiRDB on the switchover destination system determines whether the pdstj1 or the pdstj2 statistics log file will be used. The procedure for determining which statistics log file will be used is the same as when the system switchover facility is not used.
The process for collecting statistical information when in alternating status is explained below. The collection status of statistical information on the alternate BES unit determines whether or not collection of statistical information is necessary on a normal BES unit in alternating status. The same types of statistical information are collected on the normal BES unit and on the alternate BES unit. Figure 25-72 shows the process of collecting statistical information in the alternating status.
Figure 25-72 Process of collecting statistical information in alternating status
When system switchover occurs, the statistics log collection status that existed immediately before system switchover is inherited. That is, if statistics logs were being collected before the system switchover, statistics logs will continue to be collected at the switched server after system switchover, regardless of the value specified in the pd_statistics operand of the system common definition. In this case, the statistics log files are shared with the accepting unit at the switching destination. If statistics logs were not being collected immediately before system switchover, no statistics logs will be collected after system switchover; you can begin collecting statistics logs by entering the pdstbegin command after switchover.
Table 25-47 shows when statistics logs are collected when the standby-less system switchover (effects distributed) facility is used.
Table 25-47 Statistics log collection when the standby-less system switchover (effects distributed) facility is used
Unit type | Being collected | Accepting unit |
---|---|---|
Regular unit | Was being collected. | Collects. |
Was not being collected. | Does not collect. |
Figure 25-73 shows an example of statistics log collection after system switchover when the standby-less system switchover (effects distributed) facility is used.
Figure 25-73 Example of statistics log collection after system switchover when the standby-less system switchover (effects distributed) facility is used
The statistics analysis utility is executed using the created unload statistics log files as the input information. If system switchover occurs due to an error, the statistics log information immediately prior to system switchover is not acquired correctly in the file. For this reason, the execution results of the statistics analysis utility may not be accurate when used for tuning, etc.
The statistics analysis utility is executed using the unload statistics log files created at the regular unit and the accepting unit as the input information. To manually copy the files that existed prior to system switchover you must use, for example, an OS command. The statistics information on the server that has been switched is processed as information on a server belonging to the accepting unit.
If system switchover occurs because of an error, the statistics log information immediately prior to system switchover is not acquired correctly in the file. For this reason, the execution results of the statistics analysis utility may not be accurate when used for tuning, etc.