Caché Installation Guide - InterSystems Documentation

Calculating System Parameters for UNIX and Linux
Important:
If you tune maxfiles and maxfiles_lim, ensure that the values you set reflect the actual
needs of your Caché system. Caché closes all possible open file descriptors when
starting a new process via the Job command; setting a high value for these parameters
may cause unnecessary close operations which can impact job start performance.
Use the HP System V IPC Shared-Memory Subsystem to update parameters. See the HP System V Inter-
Process Communication Mechanisms online documentation page for additional information. To change
a value, perform the following steps:
1. Enter the /usr/sbin/sam command to start the System Administration Manager (SAM) program.
2. Double-click the Kernel Configuration icon.
3. Double-click the Configurable Parameters icon.
4. Double-click the parameter you want to change and enter the new value in the Formula/Value field.
5. Click OK.
6. Repeat these steps for all of the kernel configuration parameters that you want to change.
7. When you are finished setting all of the kernel configuration parameters, select Process New
Kernel from the Action menu.
The HP-UX operating system automatically reboots after you change the values for the kernel configuration
parameters.
B.2.3.3 AIX Platform Notes
The default settings of several AIX parameters can adversely affect performance. The settings and
recommendations are detailed for the following:
• I/O Pacing Parameters
• File System Mount Option
• Memory Management Parameters
• AIX Tunable Parameters
I/O Pacing Parameters
AIX implements an I/O pacing algorithm that may hinder Caché write daemons. In AIX 5.2 and AIX
5.3, I/O pacing is automatically enabled when using HACMP clustering; beginning in AIX 6.1, however,
I/O pacing is enabled on all systems and the default high-water mark is set higher than in earlier
releases.
If write daemons are slowing or stalling, you may have to adjust the high-water mark; for information,
see the “Using Disk-I/O Pacing” section of the AIX Performance Management Guide at the following
94 Caché Installation Guide