5.8.1 Notes on cluster use (common to all OSs)

• When setting up JP1/Base in a cluster system, make sure that you stop the JP1/Base services active on the physical host and existing logical hosts. If you do not stop the JP1/Base services before setting up JP1/Base, the services on the logical hosts will not operate properly. If this happens, recover by restarting the server.

• To issue events from a user application in a cluster system, use the jevsend command with the -s option specified. For the -s option, specify the event server name. This option allows issued events to be inherited from the primary node to the secondary node when a failover occurs.

• When node switching is enabled, JP1/Base does not support duplication of the event database and command execution log (ISAM) file. Use a mirror disk or RAID disk to ensure the reliability of the disk system.

• When using JP1/Base in a cluster system, specify sync for the options parameter in the event server settings file (conf). The OS normally stores data written from a program in buffer memory, and then writes it to the disk in order to improve performance. Therefore, if the system suddenly terminates because of a power failure or an error in the OS, any data not yet written to the disk will be lost. The event service suppresses this buffering to prevent data from disappearing. If you specify no-sync for the option parameter or specify neither sync nor no-sync, data might be lost. However, as data is written to the disk each time a JP1 event is issued, the performance of JP1 event issuing may be degraded. As performance varies depending on the environment, carry out investigations in advance.

• The more logical hosts you concurrently activate in a cluster system, the greater the system resources required.

• To run JP1/Base on both the logical and physical hosts in a cluster system, you must change the event service setting on the physical hosts to IP addressing. Edit the event server settings file (conf) on both the primary and secondary nodes to change the address specified in the ports parameter to the local host name, to the IP address of the local host, or to <jp1hosts2>. The event service on the physical host is set to jp1host2 (for new installations) or 0.0.0.0 (for overwrite installations from version 09-00 or earlier) by default. However, an event service (on the physical host) that is set to 0.0.0.0 cannot be activated concurrently with the event service on the logical host. For details on the event server settings file, see Event server settings file in 16. Definition Files.

• Suppose that the authentication server is used in a cluster system and JP1/IM and JP1/AJS are installed on the host on which the authentication server is set up. If the authentication server is switched during a failover, the related programs behave as follows:

  JP1/IM

  A communication error occurs. Operations are restored after the failover.

  JP1/AJS

  A communication error occurs. The user must log in again after the failover.

  You can avoid potential problems due to this behavior of JP1/IM and JP1/AJS2 by placing the authentication server on a host outside the cluster system.

• If you want to monitor files on a shared disk using the JP1/Base log file trapping function, ensure that the shared disk remains accessible while the files are being monitored. If you change the shared disk allocation during file monitoring, problems such as errors in the monitoring process and control failure in disk space allocation and deallocation could occur.

• To prevent data from being lost from the command execution log file (ISAM), specify ON for the -flush option of the jcocmddef command, enabling the command execution log to be written line-by-line to the disk. For details on the jcocmddef command, see jcocmddef in 15. Commands.

• When the function for automatically re-organizing the command execution log file is enabled, the amount of JP1/Base startup time increases in proportion to the file size. If this causes failover errors, disable this function. For details about the function for automatically re-organizing the command execution log file, see 4.9 Function for automatically re-organizing the command execution log file.

• We recommended that you set name resolution so that the IP address preferentially assigned to the physical host does not become a loop-back address (127.0.0.1) when JP1/Base of a physical host that communicates with other hosts is used in the environment where the logical host is created. Perform the settings as described below when the IP address preferentially assigned to the physical host must be a loop-back address (127.0.0.1):

  • Specify an IP address that can communicate with other hosts on the physical host using jp1hosts.

  • Specify an IP address that can communicate with other hosts in the ports parameter address of the event server setting file (conf).

  • Add the server parameter of the physical host name to the API setting file (api) and specify an IP address that can communicate with other hosts in an address of the setting file.

  For operation in an environment where the network is separated, the above setting must be performed even in the environments where the logical host was not created.

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