Use the same HiRDB system definitions in the primary system and the secondary system. Create the HiRDB system definitions for the primary system, then copy those HiRDB system definitions to the secondary system. Figures 25-32 and 25-33 show configuration examples of the HiRDB system definition files.
Figure 25-32 Configuration example of HiRDB system definition files when using the standby system switchover facility (for a HiRDB/Single Server)
Figure 25-33 Configuration example of HiRDB system definition files when using the standby system switchover facility (for a HiRDB/Parallel Server)
Copy the unit control information definition file and back-end server definition file of the normal BES unit to the alternate BES unit. Change the name of the unit control information definition file as shown below:
pdutsys.unit-identifier-of-normal-BES-unit
Of the operands specified in this definition file, those whose settings become effective during alternation are listed below. For all other operands (other than those listed below), the values that are set in the unit control information definition file of the alternate BES unit are effective.
Figure 25-34 shows a configuration example of the HiRDB system definition files when using the standby-less system switchover facility (mutual alternating configuration).
Figure 25-34 Configuration example of HiRDB system definition files when using the standby-less system switchover facility (mutual alternating configuration)
Table 25-13 shows how system definition files are used when standby-less system switchover (effects distributed) is used.
Table 25-13 Use of system definition files when standby-less system switchover (effects distributed) is used
Definition type | Use of definition files |
---|---|
System common definition | Copy files to all units within the system. Specify in the system common definition the parameters that are to be set as the default values for back-end server definitions. |
Unit control information definition | Specify only the following operands (operands that cannot be specified in the system common definition):
|
Server common definition | Copy files to all units within the HA group. |
Back-end server definition | Copy files to all units within the HA group. |
Table 25-14 explains the HiRDB system definition operands that relate to the system switchover facility.
Table 25-14 HiRDB system definition operands related to the system switchover facility
Operand name | Explanation and Notes | |
---|---|---|
pd_ha | Specifies that the system switchover facility is to be used. | |
pd_ha_ipaddr_inherit | Specifies whether or not IP addresses are to be inherited after a system switchover. Specify N for units using the rapid system switchover facility. Omit this operand for units using the standby-less system switchover facility. Y: Inherit IP addresses after system switchover. N: Do not inherit IP addresses after system switchover. | |
pd_ha_unit | Specify nouse for any unit that is not to use the system switchover facility. You must specify nouse for a recovery-unnecessary front-end server. | |
pd_ha_acttype | Specifies whether the system switchover facility is to be used in the monitor mode or the server mode. The server mode cannot be used when the system switchover facility uses Sun Cluster, HACMP, or ClusterPerfect. monitor: Operate the system switchover facility in the monitor mode. server: Operate the system switchover facility in the server mode. | |
pd_ha_restart_failure | When operating the system switchover facility in the monitor mode, specifies a command to be executed if the restarting HiRDB fails. This operand has no effect when you use the server mode. | |
pd_ha_server_process_standby | Specifies whether or not user server hot standby is to be used. Y: Use user server hot standby. N: Do not use user server hot standby. | |
pd_ha_agent | Specifies the system switchover facility to be used: standbyunit: Rapid system switchover facility server: Standby-less system switchover (1:1) facility activeunits: Standby-less system switchover (effects distributed) facility | |
pd_ha_transaction pd_ha_trn_queuing_wait_time pd_ha_trn_restart_retry_time |
| |
pd_ha_switch_timeout | This operand can be specified when the server mode is used. This operand is invalid if it is specified in the monitor mode. This operand specifies whether or not system switchover is to performed without waiting for HiRDB termination processing when termination processing of HiRDB (or the unit for a HiRDB/Parallel Server) during system switchover exceeds the server failure monitoring time. Server failure monitoring time refers to the time specified in the patrol operand of HA monitor or Hitachi HA Toolkit Extension. Y: Switch systems without waiting for HiRDB termination processing when HiRDB termination processing during system switchover exceeds the server failure monitoring time. N: Do not switch systems until HiRDB termination processing during system switchover terminates. | |
pd_ha_prc_cleanup_check | Specifies whether or not system switchover processing is to be placed on hold until HiRDB processes have terminated. For details, see 25.5.2(2) Shared disk access control. | |
pd_mode_conf | This operand is related to HiRDB (or unit) startup. Specify this operand as follows: When the monitor mode is used, specify MANUAL1. When the server mode is used, specify one of the following:
| |
pd_hostname | Specifies the standard host name of the primary system. When using the standby-less system switchover facility, specifies the unit's standard host name. (This is the same as when not using the system switchover facility.) | |
pdunit | -x | Specifies the host name of the primary system. When using the standby-less system switchover facility, specifies the unit's host name. (This is the same as when not using the system switchover facility.) |
-u | Specifies the unit identifier. | |
-d | Specifies the HiRDB directory name. When using the standby-less system switchover (1:1) facility, specify the same directory name for the normal BES unit and the alternate BES unit. When using the standby-less system switchover (effects distributed) facility, specify the same directory name for all units within the HA group. | |
-c | Specifies the host name of the secondary system. Specify this option when not inheriting IP addresses after system switchover. Omit this option when using the standby-less system switchover facility. | |
-p | Specifies the port number. Specify this option when using a utility special unit or HiRDB/Parallel Server. When using the standby-less system switchover (1:1) facility, specify the same port number for the normal BES unit and the alternate BES unit. When using the standby-less system switchover (effects distributed) facility, specify the same port number for all units within the HA group. | |
pdstart | -c | Specifies the alternate BES name. Specify this option when using the standby-less system switchover (1:1) facility. |
-g | When using the standby-less system switchover (effects distributed) facility, specify the identifier of the HA group that constitutes the set of units that become server switching destinations. | |
pdbuffer | -c | Specify this option when allocating global buffers that the alternate portion uses when alternating units. Specify this option when using a standby-less system switchover facility. For details when using the standby-less system switchover (1:1) facility, see 25.5.7 Definition of global buffers (standby-less system switchover (1:1) facility only); for details when using the standby-less system switchover (effects distributed) facility, see 25.5.8 Definition of global buffers (standby-less system switchover (effects distributed) facility only). |
pdhagroup | -g | To use the standby-less system switchover (effects distributed) facility, you define an HA group that will constitute the set of units that will become server switching destinations. Specify an identifier that will uniquely identify this HA group within the system. |
-u | Specifies the unit identifiers of the units that are to comprise the HA group. | |
pd_ha_max_act_guest_servers | When using the standby-less system switchover (effects distributed) facility, specifies the maximum number of guest BESs that will be permitted to run concurrently in a unit. | |
pd_ha_max_server_process | When using the standby-less system switchover (effects distributed) facility, specifies the maximum permissible number of active user server processes in a unit. | |
pd_ha_resource_act_wait_time | When the standby-less system switchover (effects distributed) facility is used, specifies the maximum time to wait until the running server's resources are activated when the unit is started. | |
pd_service_port | Care must be exercised in specifying this operand in a server machine configuration that includes multiple units (including a mutual system switchover configuration). For such a configuration (including a mutual system switchover configuration), use this operand to specify a separate port number for each unit in its unit control information definition. If either of the following specifications is made, system switchover to one of the units fails:
| |
pd_redo_allpage_put | When Y is specified in this operand, all pages that have been updated since a synchronization point are written into the database during full recovery processing that occurs when HiRDB is restarted. This can eliminate inconsistencies between the original and duplicate volumes that occurred during system switchover. For details about how to handle inconsistencies between the original and duplicate volume, see 18.24 Actions to take when a mismatch occurs between the original and the mirror duplicate. | |
pd_ha_mgr_rerun | When notwait is specified in this operand, HiRDB does not wait to receive a processing startup completion notice from each unit when switching system manager units (when starting processing at the switching destination). As a result, system manager units can be switched even when some units are stopped. For details about the operation method, see 25.21 Actions to take when a stopped unit prevents switching of the system manager unit. |
When the standby-less system switchover (effects distributed) facility is used, the method of determining the switching destination differs significantly from when the other system switchover facilities are used.
Because the standby-less system switchover (effects distributed) facility switches systems on a server-by-server basis, a switching destination must be specified for each server. You may specify multiple accepting units for a server. Multiple accepting units are defined as an HA group, you must specify an HA group as the switching destination for each server.
When you use the standby-less system switchover (effects distributed) facility, you can also specify the maximum number of guest BESs that will be permitted to run concurrently in each unit (pd_ha_max_act_guest_servers).
Figure 25-35 shows an example of an HA group configuration.
Figure 25-35 HA group configuration example
pdhagroup -g hag1 -u unt1,unt2,unt3,unt4 |
You use the HiRDB system definition to define an HA group. Specify a name for the HA group in the -g option of the pdhagroup operand, and specify in the -u option the unit identifiers of the units that will comprise the HA group.
You can specify only one HA group in each system definition.
The following restrictions apply to HA groups:
Each unit comprising an HA group must satisfy all the following conditions:
In the HiRDB system definition, you specify in the -g option of the pdstart command the HA group to which an accepting unit belongs.
You must specify the -g option for all servers that belong to a unit to which standby-less system switchover (effects distributed) is applicable.
You should note the following about specifying the -g option:
You can specify in the pd_ha_max_act_guest_servers operand of the unit control information definition the maximum number of guest BESs that will be permitted to operate concurrently as running systems in a unit. The purpose of this specification is to reduce the amount of resources required by guest BESs. It can also prevent excessive increases in workload.
The maximum value that can be specified in the pd_ha_max_act_guest_servers operand is the number obtained by subtracting the number of servers in the local unit from the number of servers in the HA group. If you specify a value greater than this maximum, the maximum value will be set in the pd_ha_max_act_guest_servers operand. The number of host BESs plus the value of the pd_ha_max_act_guest_servers operand cannot exceed 34.
The number of guest BESs that are in accepting status in a unit is not restricted. However, when the number of guest BESs that are operating as running systems in a unit reaches the value specified in the pd_ha_max_act_guest_servers operand, acceptability is cancelled for all the non-active guest BESs.
Once the number of erroneous BESs in an HA group exceeds the combined total number of free guest areas in the running units in the HA group, any subsequent error will cause some servers to stop and their processing will be suspended.
Once standby-less system switchover (1:1) occurs, the alternate BES unit both executes its own processes and assumes the alternate BES's processes. For this to occur, server processes are allocated to the alternate BES's original processes as well as to the normal BES's processes. The number of server processes executing the alternate BES's original processes and assuming the normal BES's processes varies according to need. However, the maximum number of active alternate BES processes (value of the pd_max_bes_process operand) is also the maximum for the combined total of the number of processes for both BESs. This prevents an excessive increase in workload at the alternate BES after system switchover. On the other hand, however, you need to be aware that the maximum number of service requests that can be processed concurrently after system switchover is limited to one half of the original. For this reason, when you specify the pd_max_bes_process operand for the alternate BES, you should take into consideration both the increase in the unit's workload and the number of service requests that can be processed concurrently.
If a safety margin has been built into the number of resident processes before system switchover (value of the pd_process_count operand), and if processes that are not actually processing service requests are resident, you have these resident processes that are not processing service requests available to assume the normal BES's processing after system switchover. As a result, processing performance after system switchover improves.
Figure 25-36 shows allocation of server processes following standby-less system switchover (1:1) (Part 1).
Figure 25-36 Allocation of server processes following standby-less system switchover (1:1) (Part 1)
Before system switchover occurs, the maximum number of processes that can be processed concurrently equals the value of the pd_max_bes_process operand specified for the alternate BES (bes1). Additionally, as many server processes as the value of the pd_process_count operand for the alternate BES (bes1) can be kept resident.
When system switchover occurs, processing for the normal BES (bes2) begins using available resident processes of the alternate BES (bes1). Therefore, there is no need to start processes for the normal BES (bes2) and the processing of the normal BES (bes2) resumes immediately following system switchover. Moreover, there is no need to start standby processes for the normal BES (bes2) before system switchover.
Once all resident processes are being used, additional processes are started as needed. However, the total number of processes is limited to the value of the pd_max_bes_process operand for the alternate BES (bes1).
Figure 25-37 shows allocation of server processes following standby-less system switchover (1:1) (Part 2).
Figure 25-37 Allocation of server processes following standby-less system switchover (1:1) (Part 2)
After system switchover, while the alternate BES (bes1) is handling the processes of the normal BES (bes2), processes that are started as needed within the value of the pd_max_bes_process operand of the alternate BES are allocated to handle the processes of the alternate BES (bes1) as well as of the normal BES (bes2).
Where there are processing requests only for the alternate BES (bes1), the number of processes up to the value of the pd_max_bes_process operand for the alternate BES (bes1) can be executed concurrently for the alternate BES (bes1).
Where there are processing requests only for the normal BES (bes2), the number of processes up to the value of the pd_max_bes_process operand for the alternate BES (bes1) can be executed concurrently for the alternate BES (bes2).
Even though standby-less system switchover (effects distributed) has occurred, an accepting unit can continue to accept guest servers until the number of running guest servers reaches the value of the pd_ha_max_act_guest_servers operand.
At an accepting unit, the host BESs and guest BESs individually start server processes up to the maximum number of processes that can be started (value of the pd_max_bes_process operand). However, the total number of server processes in a unit is limited to the value of the pd_ha_max_server_process operand. This prevents an excessive increase in workload at the accepting unit. However, you should be aware that there may be an upper limit to the number of service requests that can be processed concurrently after system switchover. For this reason, when you specify the pd_ha_max_server_process operand, you should take into consideration both the increase in the unit's workload following system switchover and the number of service requests that can be processed concurrently.
If a safety margin has been built into the number of resident processes before system switchover (value of the pd_process_count operand) and if processes that are not actually processing service requests are resident, you have these resident processes that are not processing service requests available to assume the normal BES's processing after system switchover. As a result, processing performance after system switchover improves. On the other hand, when the number of resident processes is set too large, processes that are not processing service requests may cause the number of processes to reach the value of the pd_ha_max_server_process operand. As a result, it may not be possible to process additional service requests even though the number of processes that have been started by other servers has not reached the value of the pd_max_bes_process operand. It is advisable to set the ratio between the total number of resident processes in units and the total of the maximum number of running processes to remain the same before and after guest servers are accepted. In this way, the total number of resident processes in units after guest servers are accepted is restricted by the pd_ha_process_count operand. The actual number of resident processes is either the number obtained by allocating proportionally the value of the pd_ha_process_count operand based on the values of the pd_process_count operands of the servers that are running in the unit, or the actual value of the pd_process_count operand, whichever is smaller.
The meanings of the operands related to number of processes are explained below:
Figure 25-38 shows allocation of server processes following standby-less system switchover (effects distributed) (Part 1)
Figure 25-38 Allocation of server processes following standby-less system switchover (effects distributed) (Part 1)
Before system switchover occurs, each host BES (bes1 and bes2) can execute concurrently as many processes as the value of its pd_max_bes_process operand. For each, as many server processes as the value of its pd_process_count operand can also be made resident.
When system switchover occurs, resident processes in the host BESs (bes1 and bes2) are used to provide processes for the guest BES (bes3). Therefore, there is no need to start processes for the guest BES (bes3) and processing of the guest BES (bes3) can begin immediately following system switchover. Moreover, there is no need to start standby processes for the guest BES (bes3) before system switchover.
Each server starts processes as needed up to the value of its pd_max_bes_process operand, but the combined total number of server processes in the unit is limited by the value of the pd_ha_max_server_process operand.
Also, the number of resident processes in each server is adjusted so that the combined total number of resident processes in the units equals the value of the pd_ha_process_count operand. The value of the pd_ha_process_count operand is allocated among the servers so that the number of resident processes for each server after adjustment maintains the ratio determined by each server's pd_process_count operand value.
Figure 25-39 shows allocation of server processes following standby-less system switchover (effects distributed) (Part 2).
Figure 25-39 Allocation of server processes following standby-less system switchover (effects distributed) (Part 2)
After system switchover and once the guest BES (bes3) has been accepted, the processes of the host BESs (bes1 and bes2) and the processes of the guest BES (bes3) are started, as long as the number of processes in the unit does not exceed the value of the pd_ha_max_server_process operand.
If the number of processing requests to a particular host BES (bes1, for example) is especially large, processes can be executed concurrently up to the value of the pd_max_bes_process operand of that host BES (bes1). However, the number of processing requests that can be handled by other servers (bes3, for example) decreases accordingly.