The network configuration and operating procedures depend on whether or not IP addresses are inherited after system switchover. For the applicable procedures, refer to the following sections:
This section explains the differences between network configurations.
- Guidelines
- For the standby system switchover facility, Hitachi recommends strongly that you use a system configuration that inherits IP addresses after system switchover. A system configuration that does not inherit IP addresses after system switchover will be more difficult to operate than a system configuration that does inherit IP addresses.
- Some cluster software will inherit IP addresses after system switchover and other cluster software will not. For details, see the documentation for each cluster software product.
- For units that apply the rapid system switchover facility, use a system configuration that does not inherit IP addresses after system switchover.
- Because a host that is already running takes over processing in a standby-less system switchover facility, IP addresses are not inherited.
- Use of alias IP addresses is recommended.
- When the server mode is used for the Linux version of HiRDB, a system configuration that does not inherit IP addresses is used.
- Organization of this section
- (1) When IP addresses are inherited
- (2) When IP addresses are not inherited
The two methods of inheriting IP addresses described below are as follows:
- Switching the IP address
- Switching LAN adapters
(a) Switching the IP address
You switch the IP address by using an alias IP address (you stop one IP address and start the other). In this way, you use the same IP address and host name for the primary system and the secondary system. Figure 25-26 shows a network configuration example of inheriting IP addresses (switching the IP address).
Figure 25-26 Network configuration example when inheriting IP addresses (switching the IP address)
![[Figure]](figure/zu250100.gif)
(b) Switching LAN adapters
You prepare a maintenance LAN adapter in addition to the LAN adapter that HiRDB uses and you switch the LAN adapter that is being used (stop one LAN adapter and start the other one). Then, you use the same IP address and host name for the primary system and the secondary system. Figure 25-27 shows a network configuration example of inheriting IP addresses (switching LAN adapters).
Figure 25-27 Network configuration example when inheriting IP addresses (switching LAN adapters)
![[Figure]](figure/zu250110.gif)
- Standby-less system switchover (1:1) facility
- When IP addresses are not inherited, different IP addresses and host names are used for the primary and secondary systems. This means that the host name for the secondary system must be specified in the pdunit -c operand in the HiRDB system common definition.
- Standby-less system switchover (effects distributed) facility
- Different IP addresses and host names are used for the regular unit and the accepting unit. Specifying the pdunit -c operand is not necessary.
Figure 25-28 shows an example of a network configuration when IP addresses are not inherited.
Figure 25-28 Example of network configuration when IP addresses are not inherited
![[Figure]](figure/zu250120.gif)
- Notes (applicable to the standby system switchover facility only)
- When you use HiRDB/Single Servers, specify the host name of the primary system and secondary system in the PDHOST operand of the client environment definition.
- When a unit in the system manager does not inherit IP addresses after system switchover, specify the host names of the primary system and secondary system in the PDHOST operand of the client environment definition. When a unit in the front-end server does not inherit IP addresses after system switchover, specify the host names of the primary system and secondary system in the PDFESHOST operand of the client environment definition. If you specify the host names in this manner, changing the value specified in the PDHOST or PDFESHOST operand is not necessary even after system switchover occurs.
- If the running system switches from the primary system to the secondary system when the host names of the primary system and secondary system are specified in the PDHOST operand, a UAP will attempt to connect to the primary system (standby system). Because such a UAP connects to the secondary system (running system) after the connection could not be established, the UAP processing time increases by the amount of time it takes to establish this new connection. To resolve this problem, set the host name for the client connection to an alias IP address and make sure that IP addresses are inherited. For details about specifying host names in such cases, see 25.4 Handling of host names depending on whether or not IP addresses are inherited.