The following sections contain platform-specific considerations. Review the following sections that apply to your intended installation platform:
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
AIX® implements an I/O pacing algorithm that may hinder InterSystems IRIS 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 Disk-I/O PacingOpens in a new tab in the IBM AIX documentation.
Important:
Beginning in AIX® 6.1, you should not have to make any high-water mark adjustments.
If you have questions about the impact to your system, however, contact the InterSystems Worldwide Response Center (WRC)Opens in a new tab or your AIX® supplier before making any changes. These recommendations apply to both JFS and Enhanced JFS (JFS2) file systems.
File System Mount Option
Different mount options may improve performance for some workloads.
Note:
Non-InterSystems IRIS workloads that benefit from file system caching (for example, operating system-level backups and/or file copies) are slowed by the cio mount option.
To improve recovery speed using the IRIS.WIJ file after a hard shutdown or system crash, InterSystems recommends a mount option that includes file system buffering (for example, rw) for the file system that contains the IRIS.WIJ file.
For information about mount options, see mount CommandOpens in a new tab in the IBM AIX documentation.
Memory Management Parameters
The number of file systems and the amount of activity on them can limit the number of memory structures available to JFS or JFS2, and delay I/O operations waiting for those memory structures.
To monitor these metrics, issue a vmstat -vs command, wait two minutes, and issue another vmstat -vs command. The output looks similar to the following:
# vmstat -vs
1310720 memory pages
1217707 lruable pages
144217 free pages
1 memory pools
106158 pinned pages
80.0 maxpin percentage
20.0 minperm percentage
80.0 maxperm percentage
62.8 numperm percentage
764830 file pages
0.0 compressed percentage
0 compressed pages
32.1 numclient percentage
80.0 maxclient percentage
392036 client pages
0 remote pageouts scheduled
0 pending disk I/Os blocked with no pbuf
5060 paging space I/Os blocked with no psbuf
5512714 filesystem I/Os blocked with no fsbuf
194775 client filesystem I/Os blocked with no fsbuf
0 external pager filesystem I/Os blocked with no fsbuf
If you see an increase in the following parameters, increase the values for better InterSystems IRIS performance:
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pending disk I/Os blocked with no pbuf
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paging space I/Os blocked with no psbuf
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filesystem I/Os blocked with no fsbuf
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client filesystem I/Os blocked with no fsbuf
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external pager filesystem I/Os blocked with no fsbuf
When increasing these parameters from the default values:
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Increase the current value by 50%.
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Check the vmstat output.
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Run vmstat twice, two minutes apart.
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If the field is still increasing, increase again by the same amount; continue this step until the field stops increasing between vmstat reports.
Important:
Change both the current and the reboot values, and check the vmstat output regularly because I/O patterns may change over time (hours, days, or weeks).
See the following IBM web pages for more detailed information:
AIX® Tunable Parameters
AIX® Interprocess Communication Tunable Parameters
The following table lists the tunable parameters for the IBM pSeries AIX® 5.2 operating system. None of the following listed parameters require tuning because each is dynamically adjusted as needed by the kernel. For more information, see Interprocess communication tunable parametersOpens in a new tab in the AIX documentation.
| Parameter |
Purpose |
Dynamic Values |
| msgmax |
Specifies maximum message size. |
Maximum value of 4 MB |
| msgmnb |
Specifies maximum number of bytes on queue. |
Maximum value of 4 MB |
| msgmni |
Specifies maximum number of message queue IDs. |
Maximum value of 4096 |
| msgmnm |
Specifies maximum number of messages per queue. |
Maximum value of 524288 |
| semaem |
Specifies maximum value for adjustment on exit. |
Maximum value of 16384 |
| semmni |
Specifies maximum number of semaphore IDs. |
Maximum value of 4096 |
| semmsl |
Specifies maximum number of semaphores per ID. |
Maximum value of 65535 |
| semopm |
Specifies maximum number of operations per semop() call. |
Maximum value of 1024 |
| semume |
Specifies maximum number of undo entries per process. |
Maximum value of 1024 |
| semvmx |
Specifies maximum value of a semaphore. |
Maximum value of 32767 |
| shmmax |
Specifies maximum shared memory segment size. |
Maximum value of 256 MB for 32-bit processes and 0x80000000u for 64-bit |
| shmmin |
Specifies minimum shared-memory-segment size. |
Minimum value of 1 |
| shmmni |
Specifies maximum number of shared memory IDs. |
Maximum value of 4096 |
maxuproc
maxuproc, which specifies the maximum number of processes than can be started by a single nonroot user, is a tunable parameter that can be adjusted as described in this subsection.
If this parameter is set too low then various components of the operating system can fail as more and more users attempt to start processes; these failures include loss of CSP pages, background tasks failing, etc. Therefore, you should set the maxuproc parameter to be higher than the maximum number of processes that might be started by a nonroot user (including interactive users, web server processes, and anything that might start a process).
Note:
Do not set the value excessively high because this value protects a server from a runaway application that is creating new processes unnecessarily; however, setting it too low causes unexplained problems.
InterSystems suggests that you set maxuproc to be double your expected maximum process count which gives a margin of error but still provides protection from runaway processes. For example, if your system has 1000 interactive users and often runs 500 background processes, then a value of at least 3000 would be a good choice.
The maxuproc value can be examined and changed either from the command line or from the smit/smitty administrator utilities, both as root user, as follows:
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From the command line, view the current setting:
# lsattr -E -l sys0 -a maxuproc
then modify the value:
# chdev -l sys0 -a maxuproc=NNNNNN
where NNNNNN is the new value.
-
From the administrator utility smit (or smitty) choose System Environments > Change / Show Characteristics of Operating System > Maximum number of PROCESSES allowed per user.
If you increase the value of maxuproc, the change is effective immediately. If you decrease the value of maxuproc, the change does not take effect until the next system reboot. In both cases the change persists over system reboots.
Required C/C++ Runtime Libraries
You must ensure that the required C/C++ runtime is installed on your IBM AIX® system before installing InterSystems IRIS.
InterSystems IRIS for AIX is compiled using the IBM XL C/C++ for AIX 16.1.0 compiler. If the system on which you are installing InterSystems IRIS does not have the corresponding version of the runtime already installed, you must install it. You can download the runtime from IBM XL C/C++ Runtime for AIX 16.1Opens in a new tab on the IBM Support website.
Shared Library Environment Variable for InterSystems IRIS Shared Library Support
The InterSystems IRIS shared library support contain a batch file that references any installed C linker.
If you have either the standard UNIX® C libraries or any proprietary C libraries defined in the LIBPATH environment variable, then your environment is ready.
If not, append the paths for the standard UNIX® C libraries to LIBPATH; these paths are /usr/lib and /lib.
Use of Raw Ethernet
In order to use Raw Ethernet, an IBM AIX® machine must have the DLPI (Data Link Provider Interface) packages installed. If the machine does not have the DLPI packages, obtain them from your IBM provider and create DLPI devices through the following procedure:
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Log in as root.
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In the PSE drivers section of the /etc/pse.conf file, uncomment the four lines that refer to the DLPI drivers.
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Save the file.
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Restart the computer.
If the DLPI devices are not installed, the EthernetAddress() method of the %SYSTEM.INetInfoOpens in a new tab class returns a null string rather than information about the Ethernet device.
Red Hat Linux Platform Notes
This topic includes the information on the following adjustments:
Shared Memory Limit
The default shared memory limit (shmmax) on Linux platforms is 32 MB. This value is too small for InterSystems IRIS, but it can be changed in the proc file system without a restart. The new memory limit remains in effect until you restart the Red Hat Linux system.
For example, to allow 128 MB, type the following command:
$ echo 134217728 >/proc/sys/kernel/shmmax
You can put this command into a startup script.
Alternatively, you can use sysctl(8), if available, to set this parameter permanently. Add a line to the/etc/sysctl.conf similar to the following:
kernel.shmmax = 134217728
This file is usually processed at startup, but sysctl can also be called explicitly later.
Important:
The msgmni parameter may also be set too low if you are running more than one instance of InterSystems IRIS on a machine. Set this value to three times the number of instances of InterSystems IRIS that run simultaneously on your system.
Other parameters are sufficiently sized for an InterSystems IRIS application. To view the values of other parameters, look in the files /usr/src/linux/include/asm-xxx/shmparam.h and /usr/src/linux/include/linux/sem.h.
For more information, reference “The proc File SystemOpens in a new tab” chapter of the Red Hat Enterprise Linux 4: Reference Guide.
Locked-in Memory
On Linux platforms, if shared memory is allocated in huge pages, the pages are automatically locked in memory and no further action is required. See the Configuring Huge Pages on Linux section in this chapter for information about allocating huge pages.
If not using huge pages, you can configure InterSystems IRIS to lock the shared memory segment in memory to prevent paging. This is described in the LockSharedMemory section of the “memlock” entry in the Configuration Parameter File Reference.
Otherwise, you must increase the maximum size that may be locked into memory. The default value is 32 KB. View the current value using the ulimit command.
For example, to display all current limits:
bash$ ulimit -a
core file size (blocks, -c) unlimited
data seg size ( KBytes, -d) unlimited
file size (blocks, -f) unlimited
pending signals (-i) 1024
max locked memory (KBytes, -l) 32 <---------- THIS ONE
max memory size (KBytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
stack size ( KBytes, -s) 10240
cpu time (seconds, -t) unlimited
max user processes (-u) 49000
virtual memory ( KBytes, -v) unlimited
file locks (-x) unlimited
To display only max-locked memory, use the -l option:
bash$ ulimit -l
32
If you have privileges, you can alter the value directly using the ulimit command; however, it is better to update the memlock parameter in the /etc/security/limits.conf file. If the memlock limit is too low, Linux reports a ENOMEM - "Not enough memory" error, which does not make the cause obvious. The actual memory is allocated; it is the lock that fails.
For more information, see memlock in the Configuration Parameter File Reference.
Adjusting for Large Number of Concurrent Processes
Make the following adjustments if you are running a system that requires a large number of processes or telnet logins.
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In the /etc/xinetd.d/telnet file, add the following line:
instances = unlimited
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In the /etc/xinetd.conf file, add or change the instances setting to:
instances = unlimited
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After you make these modifications, restart the xinetd services with:
# service xinetd restart
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The default pty (pseudo terminal connection) limit is 4096. If this is not sufficient, add or change the maximum pty line in the /etc/sysctl.conf file. For example:
kernel.pty.max=10000
Dirty Page Cleanup
On large memory systems (for example, 8GB or larger), when doing numerous flat-file writes (for example, InterSystems IRIS backups or file copies), you can improve performance by adjusting the following parameters, which are located in proc/sys/vm/:
-
dirty_background_ratio — Maximum percentage of active that can be filled with dirty pages before pdflush begins to write them. InterSystems recommends setting this parameter to 5.
-
dirty_ratio — Maximum percentage of total memory that can be filled with dirty pages before processes are forced to write dirty buffers themselves during their time slice instead of being allowed to do more writes. InterSystems recommends setting this parameter to 10
You can set these variables by adding the following to your /etc/sysctl.conf file:
vm.dirty_background_ratio=5
vm.dirty_ratio=10
These changes force the Linux pdflush daemon to write out dirty pages more often rather than queue large amounts of updates that can potentially flood the storage with a large burst of updates.”
Using Kerberos
To use Kerberos on the Red Hat Linux platform, you must install the krb5-devel package in addition to the krb5-libs package. Installing krb5-devel establishes the required symbolic links for using Kerberos. The package is required for production environments, not only development environments. See the Red Hat NetworkOpens in a new tab web site for more information about these components.
SUSE Linux Platform Notes
This topic includes the information on the following adjustments:
Shared Memory Limits
The default shared memory limits (shhmax and shmall) on SUSE Linux 32-bit platforms are too small for InterSystems IRIS, and can be changed in the proc file system without a restart.
InterSystems IRIS uses shared memory for database buffers, global buffers, routine buffers, as well as license use. If the machine is being used only for InterSystems IRIS, InterSystems recommends setting the shared memory to approximately half the total memory. For more information, see Memory Planning in System Resource Planning and Managment, as well as Memory and Startup Settings and Determining License Capacity and Usage in the System Administration Guide.
Note:
The recommendations to change the shared memory limits do not apply to SUSE Linux 64-bit systems.
For example, to allow 512 MB, type the following commands:
#sets shmall and shmmax shared memory
echo 536870912 >/proc/sys/kernel/shmall #Sets shmall to 512 MB
echo 536870912 >/proc/sys/kernel/shmmax #Sets shmmax to 512 MB
You can put these commands into a script that is run at startup. The SUSE Linux product documentation recommends you put the commands in the /etc/init.d/boot.local script file.
You can change the settings for the system memory user limits by modifying a file called /etc/profile.local. Add lines similar to the following:
#sets user limits (ulimit) for system memory resources
ulimit -v 512000 #set virtual (swap) memory to 512 MB
ulimit -m 512000 #set physical memory to 512 MB
In this same file, you can permanently change the values for the PATH and CLASSPATH parameters by adding lines similar to the following:
#sets env values PATH and CLASSPATH
export PATH=$PATH:/usr/iris/bin:/path/to/j2sdk/bin:/.
export CLASSPATH=
$CLASSPATH:/iris/dev/java/lib/JDK18/intersystems-jdbc-3.0.0.jar.
Important:
To avoid the risk of losing your changes during system upgrades, do not change the /etc/profile file.
Locked-in Memory
On Linux platforms, if shared memory is allocated in huge pages, they are automatically locked in memory and no further action is required. See Configuring Huge Pages on Linux for information about allocating huge pages.
If not using huge pages, you can configure InterSystems IRIS to lock the shared memory segment in memory to prevent paging. This is described in the LockSharedMemory section of the “memlock” entry in the Configuration Parameter File Reference.
Otherwise, you must increase the maximum size that may be locked into memory. See the Locked-in Memory section of the Red Hat Linux Platform Notes in this chapter for instructions.
Using Kerberos
To use Kerberos on the SUSE Linux platform, you must install the krb5-devel package in addition to the krb5-libs package. Installing krb5-devel establishes the required symbolic links for using Kerberos. The package is required for production environments, not only development environments. See the SUSE documentationOpens in a new tab web site for more information about these components.
