Specifies the number of processes that can be made resident in the single server. A resident process is a process that is activated at the time the server is started.
Advantage
By activating the processes used by transactions that can be processed concurrently by the single server at the time of system startup and keeping them resident, the process startup time can be reduced even when new transactions are entered. However, HiRDB startup will take longer.
Specificationguidelines
The value to be specified is determined on the basis of the process private area of the single server's server process and the real memory size of the processor. For details about the process private area of server processes, see the HiRDB Version 9 System Operation Guide.
If a multi front-end server configuration is used and the pd_max_bes_process or pd_max_dic_process operand is also specified, specify for the pd_process_count operand a value that satisfies the following condition: Value of pd_process_count (value of pd_max_bes_process or value of pd_max_dic_process)
The value specified for this operand must be no more than the maximum number of processes that can be activated for the single server (value of pd_max_users + value of pd_max_reflect_process_count).
Tuningthespecifiedvalue
For details about how to tune the resident processes count, see the HiRDB Version 9 System Operation Guide.
Notes
Because the number of resident processes has a direct effect on the availability of memory space and on the CPU, specifying an unnecessarily large number might prevent HiRDB from starting or might degrade the server machine's processing performance.
If more processes than the resident process count are needed, additional processes are dynamically started, up to the maximum processes count allowed. However, depending on the value specified for the pd_max_server_process operand, it might not be possible to start all of the processes indicated by the maximum processes count.
Operanddefault
When this operand is omitted (or 0 is specified), the specification of the same operand in the server common definition is assumed. When the same operand is also omitted in the server common definition, the default is the maximum number of processes.
resident-processes-count-at-server-startup
Specifies the number of processes that can be made resident during HiRDB startup.
It is common for resident processes to be activated during HiRDB startup. If there are many resident processes, the amount of time required for HiRDB startup increases proportionately. For example, it takes approximately 1 second to activate a process on a server machine with a 100-MIPS performance rating.
The differences in processing that result depending on whether a resident processes count at server startup is specified are as follows:
When there is no specification of a resident processes count at server startup (when, for example, pd_process_count = 500 is specified) All 500 resident processes are activated during HiRDB startup, and HiRDB will not start until they are all activated. In this example, it would take a 100-MIPS server machine about 500 seconds to activate all the resident processes during HiRDB startup.
When a resident processes count at server startup is specified (when, for example, pd_process_count = 500, 50 is specified) Some of the resident processes (50 in this case) are activated during HiRDB startup, and the remaining resident processes are activated after HiRDB startup. HiRDB can be started as long as the specified number of resident processes are activated. In this example, it would take a 100-MIPS server machine about 50 seconds to activate 50 resident processes during HiRDB startup. The remaining 450 resident processes (in this example) would be activated after HiRDB startup.
Advantage
The amount of time required for HiRDB startup is reduced. Use this option when you want to reduce the HiRDB startup time as much as possible, such as when you are using the system switchover facility.
Specificationguideline
Specify a value equal to the number of processes that will be required immediately after HiRDB startup is completed.
Notes
When you specify a resident processes count at server startup, recheck the value in the PDCWAITTIME operand of the client environment definition.
If more UAPs than the resident processes count at server startup are to be executed immediately following HiRDB startup, transaction processing might not be performed until after the remaining resident processes have been activated. Therefore, if the value specified in the PDCWAITTIME operand of the client environment definition is small, it might not be possible to process some UAPs due to timeouts. For details about the PDCWAITTIME operand, see the HiRDB Version 9 UAP Development Guide.
Specifies in minutes the interval for checking for nonresident server processes in HiRDB that are to be stopped. The facility for stopping nonresident server processes is applied when the number of executing server processes exceeds the number of processes that can be made resident (value specified by the pd_process_count operand). The number of server processes that the facility stops is computed automatically by HiRDB.
Advantages
This facility improves the utilization rates of the memory and of process resources because it increases the number of nonresident processes that can be reused when the workload (number of server processes that are executing) peaks.
Specificationguidelines
For example, if there is only one hour a day during which peak workload occurs and the intervals between peaks within that hour are approximately two minutes apart, specify 2 for this operand.
This facility does not have any effect if the number of server processes that execute concurrently during peak periods is always fewer than the number of resident processes. In this case, omit this operand.
Operand default
When this operand is omitted, the specification of the same operand in the server common definition is assumed. When the same operand is also omitted in the server common definition, the default is 0.
Tuningthespecifiedvalue
Collect statistical information on system operations for each server for one week. Determine the workload peaks from the number of server processes being serviced (# OF PROCESSES ON SERVICE). If that peak value exceeds the currently set number of processes that can be made resident (value specified by the pd_process_count operand), determine the interval between individual peaks and set that number of minutes.
However, if there are ample resources, such as memory and CPU, in the server machine, adding the shortfall in the number of processes to the number of resident processes (in other words, increasing the value of the pd_process_count operand) is more effective in improving performance than specifying the pd_server_cleanup_interval operand.
Note
When this operand is omitted or 0 is specified, the system checks every 10 seconds for nonresident server processes that are waiting to be serviced and stops any such processes that are found.
This operand need not be specified for the Linux edition.
Specifies the maximum size of memory used by each server process processed by a single server. If at the applicable trigger point shown below the amount of memory being used by a server process exceeds the value specified here, that server process is terminated. When a server process is so terminated, the KFPS00350-w message is output. This is called the facility for monitoring the memory size of server processes; for details, see the HiRDB Version 9 System Operation Guide.
Server type
Process name
Process termination trigger
Single server
pdsds
At UAP disconnection
At utility termination
Advantages
The facility for monitoring the memory size of server processes resolves the following problem:
The memory size of a server-resident process becomes too large during a particular SQL processing, significantly reducing the amount of system memory that is available.
When a utility is running, specifying large values for the sizes of local and work buffers used for sorting will increase the amount of memory used by server resident processes and decrease available system memory.
The HiRDB server releases memory space that is no longer needed. However, even when a program releases memory, the OS holds the memory area itself in the memory management facility inside the applicable process. Consequently, a process that becomes large in terms of using a large memory area even once never shrinks and continues to have an adverse impact on the system, especially in the case of resident processes. The facility for monitoring the memory size of server processes can prevent memory shortages because it terminates even resident processes.
Application criterion
Apply this facility when the amount of memory space used by a HiRDB server process becomes large, resulting in memory shortages.
Specification guidelines
Maximum value for this operand Normally specify a value by considering the maximum processing capability of HiRDB. Assuming the maximum number of SQL statements that can execute concurrently, which is dependent on the maximum number of concurrent connections, determine for this operand a value that satisfies the following condition in each unit: a (b + c) < d a: Number of server processes in the unit (maximum number of concurrent connectionsnumber of servers in the unit) b: Virtual memory size for one server process immediately following HiRDB startup c: pd_svr_castoff_size operand value d: Memory size that can be allocated to a unit (memory size excluding the area used by other programs)
Minimum value for this operand If the value specified for this operand is smaller than the memory size needed for normal SQL processing, the efficiency of making processes resident will deteriorate, resulting in frequent process terminations and restarts. Each time this occurs, a message is output to the syslogfile or the message log file, resulting in further performance degradation. To prevent this, select for this operand a value that satisfies the following condition for each server: a - b < c a: Server process virtual memory size following SQL process termination or utility termination b: Virtual memory size for server process immediately following HiRDB startup c: pd_svr_castoff_size operand value
The virtual memory size can be determined by an OS command (for example, the top command in HP-UX).
Operand default
When this operand is omitted, the specification of the same operand in the server common definition is assumed. When the same operand is also omitted in the server common definition, the default is 0.
Operand rule
When 0 is specified for this operand, the facility for monitoring the memory size of server processes is not applied.
Specifies the maximum number of files and pipes accessed by HiRDB processes.
Specification guidelines
Omit this operand if the maximum number of the plug-in index storage RDAREAs updated in a single transaction is less than 100.
If the maximum number of the plug-in index storage RDAREAs updated in a single transaction is equal to or greater than 100, specify the maximum number + 320 for this operand.
Notes
SQL errors might result if a small value is specified.
The maximum value of this operand differs depending on the OS type as follows: HP-UX: 8192 Solaris: 2048 64-bit mode Solaris: 8192 AIX: 8192 Linux: 8192
This operand's value is not applicable when the following operations are performed: The database creation utility, database reorganization utility, or rebalancing utility is used to create an index information file. The database creation utility is used to create a divided-input data file. In these cases, the following value is used: MIN(A, B) A: Maximum value of the pd_max_open_fds operand for the OS being used, as explained above. B: Physical upper limit for the number of files that can be opened or locked by a single process according to the OS's operating system parameter shown below: For HP-UX: Value of maxfiles_lim For Solaris: Value of rlim_fd_max For AIX: Value of nofiles_hard For Linux: Value of hardnofile
Specify this operand if you use the asynchronous READ facility. For this operand, specify the number of processes necessary for asynchronous READ operations. For details about the asynchronous READ facility, see the HiRDB Version 9 Installation and Design Guide.
Condition
A value of 1 or greater must be specified for the -m option of the pdbuffer operand.
Advantage
The asynchronous READ facility is especially effective (improves performance) when character special files, for which input and output take a long time, are used. Conversely, when regular files or Hitachi disk array system disks are used, for which input and output do not take a long time, the asynchronous READ facility might not have much effect for the following reasons:
Input/out time does not overlap with CPU time most of the time.
Communication processing has a large overhead.
Specification guidelines
Specify 0 or 1. However, if a value between 2 and 256 is specified for the -m option of the pdbuffer operand, specify the same value as the -m option value. If a value greater than 256 is specified for the -m option, specify the same value as the number of disk devices that store RDAREAs and system files or 256.
Increasing the value of this operand can shorten the processing time when the degree of concurrency is high for the SQL statements to which the asynchronous READ facility is applied. Decreasing the value of this operand might increase the processing time when the degree of concurrency is high for the SQL statements to which the asynchronous READ facility is applied. This is because asynchronous READ processes might have to wait for processing completion.
Because a number of processes equaling value of this operandserver count are started, determine a value for this operand by taking resources (shared memory and message queue) into consideration. For details about estimating shared memory and message queue sizes, see the HiRDB Version 9 Installation and Design Guide.
Tuningthespecifiedvalue
For details about how to tune the specification value (number of asynchronous READ processes), see the HiRDB Version 9 System Operation Guide.
Operand default
When this operand is omitted, the specification of the same operand in the server common definition is assumed. When the same operand is also omitted in the server common definition, the default is 0.
Operand rule
If you specify 0 for this operand, the asynchronous READ facility is not used.
Relationshiptootheroperands
If you change the value of this operand, re-evaluate the value of the pd_max_server_process operand.
Effects on individual estimation formulas
If the value of the pd_max_ard_process operand is changed, the following estimation formulas are affected:
HiRDB Version 9 Installation and Design Guide:
Processes started by a HiRDB single server configuration
Formula for size of shared memory used by global buffers under Estimating the memory size required for a HiRDB single server configuration
Calculation of required memory under Estimating the memory size required for a HiRDB single server configuration
Estimating HP-UX OS parameter values
Formula 2 under Formulas for shared memory used by a single server
HiRDB single server configuration under Determining Environment Variables Related to the Number of Resources
Specify this operand when you use the facility for parallel writes in deferred write processing for all buffer pools. Specify for this operand the number of processes to be processed in parallel. Increasing the number of processes can shorten the write processing time. For details about the facility for parallel writes in deferred write processing, see the HiRDB Version 9 Installation and Design Guide.
Specification guidelines
Specify 2, which is the smallest value that enables the facility for parallel writes in deferred write processing. Furthermore, to determine the value for this operand, see Tuning deferred write processing in the HiRDB Version 9 System Operation Guide.
Note
Specifying the facility for parallel writes in deferred write processing increases the number of processes and consequently raises the CPU usage rate.
Effects on individual estimation formulas
If the value of the pd_dfw_awt_process operand is changed, the following estimation formulas are affected:
HiRDB Version 9 Installation and Design Guide:
Processes started by a HiRDB single server configuration
Calculation of required memory under Estimating the memory size required for a HiRDB single server configuration
Formula 5 under Formulas for shared memory used by a single server
HiRDB single server configuration under Determining Environment Variables Related to the Number of Resources