10.3.11 Operands related to system log files

22) pd_log_max_data_size = log-input/output-buffer-size
~<unsigned integer>((32000-523000)) (bytes)
Operand default value
  • Default value in recommended mode: 523000
  • Default value in 0904 compatibility mode: 400000
Specifies in bytes the size of the buffer to be used for system log input/output operations.
Specification guidelines
  • For a HiRDB single server configuration:
    Change the specification value according to the tuning method.
  • For a HiRDB parallel server configuration:
    Specify a value that satisfies conditional expression 1 below. If uap is specified in the pd_rpl_reflect_mode operand or a recovery-unnecessary front-end server is used, specify a value that satisfies both the conditional expressions below (1 and 2). To optimize the value, use the tuning method for the specification value.
    Conditional expression 1: log input/output buffer length [Figure]a
    a: 72 [Figure] (maximum number of back-end and dictionary servers that are targets for reference or update processing by a single transaction) + 1,344
    Conditional expression 2: log input/output buffer length [Figure]b
    b: (maximum number of back-end and dictionary servers that are targets for reference or update processing by a single transaction + 1) [Figure] 128 + 64
Tuning the specified value
A value (other than the default value) might need to be specified for this operand after the following types of statistics analysis utility (statistical information related to system operation) have been checked:
  • Number of buffer sectors waiting for input/output (# OF BUFFER FOR WAIT I/O)
    If the average number of buffer sectors waiting for input/output significantly exceeds 100, increase the value for this operand so that the average approaches 100.
  • Number of waits caused by lack of a current buffer (# OF WAIT THREAD)
    If the number of waits caused by lack of a current buffer is not 0, increase the value for this operand.
Note
The specification of this operand affects the response and throughput of SQL code executed by a transaction. When a small value is specified, writing to system log files occurs frequently, which might result in deterioration of performance.
Relationship to other operands
  • Use this operand and the pd_log_write_buff_count operand to determine the log I/O buffer size.
23) pd_log_rec_leng = system-log-file-record-length
~<unsigned integer>((1024, 2048, 4096)) (bytes)
Operand default value
  • Default value in recommended mode: 1024
  • Default value in 0904 compatibility mode: 4096
Specifies the record length for the system log files; the specifiable values are 1024, 2048, and 4096.
Specification guidelines
Specify the record length based on the guidelines for designing the record length of system log files. For details about the guidelines for designing the record length of system log files, see Record length of a system log file in the HiRDB Version 9 Installation and Design Guide.
Notes
  • If a value that is different from the record length specified by the -l option of the pdloginit command is specified for this operand, system log files cannot be opened.
  • For details about how to modify the system log file record length, see the HiRDB Version 9 System Operation Guide.
24) pd_log_rollback_buff_count = rollback-log-input-buffer-sector-count
~<unsigned integer>((0-256))
Operand default value
  • Default value in recommended mode: 0
  • Default value in 0904 compatibility mode: The default value is shown below.
    [Figure]Standby-less system switchover (1:1) facility is used in the unit
    Number of alternate back-end servers[Figure] 2
    [Figure]Standby-less system switchover (effects distributed) facility is used in the unit
    (Number of host back-end servers + value of pd_ha_max_act_guest_servers) [Figure] 2
    [Figure]All other cases
    Number of servers in the unit[Figure] 2
Specifies the number of buffer sectors to be used for system log input during rollback processing. If 0 is specified in this operand, HiRDB determines the number of rollback log input buffer sectors.
Specification guidelines
  • We recommend that you specify 0 in this operand, in which case HiRDB will calculate an appropriate value automatically.
  • If the specified value is too small, concurrent execution of rollbacks might be slowed. If the specified value is too large, the unit controller might use more shared memory than is necessary.
Tuning the specified value
Specify 0 in this operand. If specifying 0 leads to memory shortages, do not specify this operand.
Effects on individual estimation formulas
If the value of the pd_log_rollback_buff_count operand is changed, the following estimation formulas are affected:
HiRDB Version 9 Installation and Design Guide:
  • Formulas for shared memory used by a unit controller under Estimating the memory size required for a HiRDB single server configuration
  • Formulas for shared memory used by a unit controller under Estimating the memory size required for a HiRDB parallel server configuration