When you configure a system with many units or servers, you must reduce the communications load by locking the ports that HiRDB uses. To do this, specify the system definition operands shown in the table below.

Table 9-8 Operands that must be specified to reduce the communications load

No.	Operand	Description
1	pd_name_fixed_port_lookup=Y	Specify Y for this operand and use the unit's own shared memory information so that it communicates with other units. Also specify the operands shown in No. 2.
2	pd_mlg_port or the pdunit -m option pd_alv_port or the pdunit -a option pd_trn_port or the pdunit -t option pd_scd_port or the pdunit -s option pd_name_port or the pdunit -p option	--
3	pd_ipc_conn_nblock_time	When HiRDB is performing communication between servers and there is a server that is not running, the next operation is pended by the amount of time specified in this operand. For that reason, specifying too high a value for this operand might cause performance to decline. In systems without a high network load, specify 2 (seconds) for this operand. In systems with a high network load, do one of the following. Determine the value for this operand according to the network environment. Consider modifying or upgrading your network environment.
4	pd_bes_connection_hold=Y	No particular specification.
5	pd_bes_conn_hold_trn_interval	If the UAP connection time (from SQL CONNECT to DISCONNECT) is short, specify 0 for this operand.

Legend:

--: Not applicable

Use the high-speed connection facility to reduce the communication load. For details about the high-speed connection facility, see the HiRDB Version 9 UAP Development Guide.

The maximum number of units that can be defined for a single HA group is 32. So if the number of units is 33 or more, define multiple HA groups. For details about the standby-less system switchover (effects distributed) facility, see the HiRDB Version 9 System Operation Guide.

When you have high numbers of units or servers, you must also set an upper limit for the number of open files. Determine a value for the operating system parameter (for HP-UX, maxfiles_lim; for Solaris, rlim_fd_max; for AIX, nofiles_hard; and for Linux, hard nofile) that sets the physical limit value for the number of files that can be opened or locked by a single process. For details about the operating system parameters, see Chapter 20. Specifying OS Parameters.

The TCP/IP Listen queue used during communications might run short. To prevent this, make sure that the Listen queue specification is not too small. For details about how to specify the Listen queue, see 20.6 Listen queue specified values.

The number of ports used during communications might run short. To prevent this, you need to take steps to keep a port shortage from developing. For details about how to configure these settings, see 22.4.4 Ways to avoid a shortage of ports.