21.3 Estimating AIX 5L OS parameter values

This section describes the procedures for estimating the HP-UX OS parameter values (or kernel parameter values). If OS parameter values are too small, HiRDB may not function correctly. Table 21-3 shows the guidelines for the HP-UX OS parameter values.

Table 21-3 Guidelines for the AIX 5L OS parameter values

OS parameterGuideline for value
data_hardThe parameter default value is -1 (unlimit). Do not specify this if there is no particular reason to do so.
stack_hardThe parameter default value is -1 (unlimit). Do not specify this if there is no particular reason to do so.
nofilesHiRDB calculates and sets this value, so you do not need to specify it.
nofiles_hardThe parameter default value is -1 (unlimit). Do not specify this if there is no particular reason to do so.
maxuprocSpecify at least MAX(value of pd_max_server_process + e, 512).
However, if this value is less than the value required by another program that runs on the server machine, specify the higher value.
EXTSHM environment variableFor the 32-bit mode, specify ON. For the 64-bit mode, specification of this parameter is not needed.
e: Maximum number of concurrently executable commands (including utilities)
Note
  • The maximum number of files that can be opened in the system concurrently can be controlled by maxuproc[Figure]nofiles[Figure]number of fixed licenses.
  • The maximum number of users who can log in to the system can be controlled by the number of fixed licenses.
  • The maximum number of processes that can execute concurrently in the entire system can be controlled by maxuproc[Figure]number of fixed licenses.
Organization of this section
(1) Specifying parameters unique to AIX 5L

(1) Specifying parameters unique to AIX 5L

(a) Specifying environment variables

For AIX 5L, you need to specify the following environment variables in the system common definition.

#
The page fix facility of shared memory is used when you specify fixed in the pd_shmpool_attribute operand or pd_dbbuff_attribute operand. For details, see pd_shmpool_attribute operand or pd_dbbuff_attribute operand in the manual HiRDB Version 8 System Definition.
(b) Notes on the /etc/security/limits file specification values

Root users and HiRDB administrators must pay attention to the following specification values:

(c) Specifying the Virtual Memory Manager (VMM) tuning parameters

Specify the following parameters when using specific facilities. You can set the VMM parameters using the vmo command (AIX 5L 5.2 and later) or vmtune command (AIX 5L 5.1) of AIX 5L. For details about the vmo and vmtune commands, see the documentation for AIX.

(d) Restricting the core file output information

In AIX 5L V5.2 or AIX 5L V5.3, specify the following parameters to exclude the shared memory area in the core file that is output when a process failure occurs.

(e) Notes on bogging down of programs due to high I/O load on the JFS/JFS2 file system

Execution of programs that send requests to the JFS/JFS2 file system for large output can cause the performance of system disk I/O to degrade. Programs such as pdcopy, or the compress, cp, and dd commands for large size files can cause programs running on the same system to stall for up to 20 to 30 seconds.

In particular, if the system operates with a cluster configuration that uses HA monitor or HACMP to monitor system response time, system switchover might occur.

To minimize this problem, you can equalize the write request frequency from application programs by setting an OS parameter for the system parameter (sys0). By specifying the following OS parameters, you can control I/O requests so that large numbers of I/O requests not completed for writing to the disk device do not accumulate in the file cache.

OS parametersGuide to specification value#
maxpout33
minpout16
#
The optimum setting value of the maxpout/minpout parameter depends on the system configuration or I/O characteristics of applications.
Therefore, it is effective to set a value listed in the above table and increase the value until application I/O performance is acceptable.
For details about the maxpout/minpout parameter setting values, see thedocumentation for the OS.