7.1.2 Prerequisites for cluster operation (for Windows)

JP1/IM - Manager runs in a logical host environment in a cluster system and supports failover. The prerequisites for running JP1/IM - Manager in a logical host environment are the allocation and release of the shared disk and logical IP addresses, and normal control of operation monitoring by the cluster software.

Important: Depending on the system configuration and environment configuration, the cluster software supported by JP1/IM - Manager might not always meet the prerequisites described here. Evaluate the system configuration and environment configuration so that the prerequisites are satisfied.

Organization of this subsection

(1) Prerequisites for the logical host environment
(2) Prerequisites for the physical host environment
(3) JP1's support range
(4) Physical host names
(5) Logical host names

(1) Prerequisites for the logical host environment

When JP1/IM - Manager is to be run in a logical host environment, the prerequisites with respect to logical IP addresses and the shared disk that are described in the table below must be satisfied.

Table 7‒1: Prerequisites for the logical host environment
Logical host component	Prerequisites
Shared disk	A shared disk that can be inherited from the primary node to the secondary node must be available. The shared disk must have been allocated before JP1 was started. Allocation of the shared disk cannot be released during JP1 execution. Release of the shared disk allocation must not occur until after JP1 has terminated. The shared disk must be managed so that it will not be accessed illegally by multiple nodes. Files must be protected by a method such as a file system with a journal function so that the files will not be deleted in the event of a system shutdown. The contents of files must be protected and inherited in the event of a failover. Forced failover must be available in the event the shared disk is being used by a process at the time of a failover. In the event of a failure on the shared disk, the cluster software must be able to manage the recovery procedure so that JP1 does not have to handle the recovery. If JP1 needs to be started or terminated as an extension of recovery processing, the cluster software must issue the startup or termination request to JP1.
Logical IP addresses	Inheritable logical IP addresses must be available for communications. It must be possible for a unique logical IP address to be obtained from the logical host name. The logical IP addresses must be allocated before JP1 starts. The logical IP addresses cannot be deleted during JP1 execution. The correspondence between the logical host name and a logical IP address cannot change during JP1 execution. The logical IP addresses must not be deleted until after JP1 has terminated. In the event of a network failure, the cluster software must be able to manage the recovery procedure so that JP1 does not have to handle the recovery. If JP1 needs to be started or terminated as an extension of recovery processing, the cluster software must issue the startup or termination request to JP1.

If any the above conditions are not satisfied, problems such as the following might occur during JP1 operation:

Data written by the primary node becomes corrupted during failover

Normal operation cannot be achieved due to problems with JP1, such as errors, data loss, or startup failure.
Recovery processing is disabled due to a LAN board failure

JP1 cannot operate normally due to communication errors until the LAN boards are swapped or a failover to another server is achieved by a means such as the cluster software.

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(2) Prerequisites for the physical host environment

In a cluster system where JP1/IM - Manager is run on a logical host, the physical host environment for each server must meet the prerequisites described below.

Table 7‒2: Prerequisites for the physical host environment
Physical host component	Prerequisites
Server core	The physical host environment must utilize a cluster configuration consisting of two or more server systems. CPU performance must be high enough for processing to be executed. (For example, if multiple logical hosts are run concurrently, the CPU must be capable of handling the processing.) There must be sufficient real memory for the processing that is to be executed. (For example, if multiple logical hosts are run concurrently, the size of the real memory must be adequate.)
Disk	Files must be protected by a method such as a file system with the journal function so that files will not be lost in the event of a system shutdown.
Network	It must be possible to establish communication using IP addresses that correspond to the physical host names (host names that are displayed when the `hostname` command is executed). (It must not be possible for a program such as the cluster software to set a status that disables communication.)^# Correspondence between host names and IP addresses cannot be changed during JP1 operation. (It must not be possible for programs, such as the cluster software and name server, to change the correspondence.) In Windows, the LAN board corresponding to a host name must have priority in the network bind settings. (Priority cannot be given to any other LAN board, such as for heartbeat.)
OS, cluster software	JP1 must support the cluster software and version being used. All patches and service packs required by JP1 and the cluster software must have been installed. Each server's environment must have been set up appropriately so that the same processing can be performed in the event of failover.
Service	For a remote monitoring configuration, the JP1/Base log file trap service must be running.

#: With some cluster software, the IP address corresponding to a physical host name (host name that is displayed when the hostname command is executed) might not be usable for communication. In such a case, JP1 cannot be run in the physical host environment. Use JP1 only in the logical host environment.

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(3) JP1's support range

When JP1 is run on a logical host in a cluster system, the range controlled by JP1 is JP1 itself. Control of the logical host environment (shared disk and logical IP addresses) and the JP1 startup and termination timing depend on the control by the cluster software.

If the prerequisites for the logical host environment and physical host environment discussed above are not satisfied, or there are problems in the control of the logical host environment, there will be problems with the JP1 operations as well. In such a case, the problems must be dealt with by the OS and cluster software that controls the logical host environment.

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(4) Physical host names

When IM databases are used, a physical host name must be a character string of not more than 32 characters consisting of only one-byte alphanumeric characters, -, and . (period).

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(5) Logical host names

Note the following when you specify a logical host name:

The logical host name must be specified in the hosts file or on the name server to enable TCP/IP communication.
JP1/Base, the prerequisite product, must be able to handle the logical host name. For details, see the JP1/Base User's Guide.
When IM databases are used, a logical host name must be a character string of not more than 32 characters consisting of only one-byte alphanumeric characters and one-byte hyphens (-).

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