Running multiple instances of IBM HTTP Server from a single install

Run multiple, independent instances of IBM® HTTP Server from a single installation. It is seldom necessary to run multiple instances, as features like virtual hosts allow a single instance to efficiently serve many sites, but it some cases it is necessary. If you need to securely administer your sites by different administrators, for example, you must run separate instances that each use their own configuration files.

Before you begin

This topic is primarily for AIX®, HP-UX, Linux®, Solaris, and Windows operating systems. On the z/OS® platform, the install_ihs command creates a separate directory for each instance without creating another copy of the product. See the z/OS topic for configuring IBM HTTP Server for more information.

Before configuring multiple instances, consider if your problem can be solved by using virtual hosts and/or having IBM HTTP Server listen on multiple addresses and ports. The advantage of a single instance is that it uses less resources to serve the same requests as multiple instances.

Avoid trouble: When you follow the examples, change "this_instance" to a unique name for each instance.

Procedure

Create a separate main configuration file, normally the httpd.conf file, for each instance.
Best practice: To reduce duplication, store common directives in common files and import these into the separate, main configuration files with the Include directive.
We'll call the configuration file conf/this_instance.conf for the rest of these steps.
Here is a simple example of a configuration file for an instance:
```
Listen 10.0.0.1:80
PidFile instance1/httpd.pid
ErrorLog instance1/error.log
CustomLog instance1/access.log common
# Other directives that make this instance behave uniquely
Include conf/common.conf
```
A real configuration file would have more directives in it to make this instance behave differently than the other instances.
Configure the port settings in the configuration files.
You cannot use a combination of listen port and listen IP address for more than one instance. Check the Listen directives in each configuration file, and verify that they are unique. See information on the Listen directive for Apache HTTP Server for more information.
Configure settings for logging and other special files.
Any files that are normally stored in the install_root/logs directory cannot be shared between instances. Each instance must have unique values for the following directives:
PidFile

Applicable to all configurations. See the information on the PidFile directive for Apache HTTP Server.

ScriptSock

Applicable to non-Windows configurations with mod_cgid enabled.

ErrorLog

Applicable to all configurations. See the information on the ErrorLog directive for Apache HTTP Server.

CustomLog or TransferLog

Applicable to all configurations. See the information on the CustomLog directive or the TransferLog directive for Apache HTTP Server.

SSLCachePortFilename

Applicable to all non-Windows configurations with SSL enabled. See the information on the SSLCachePortFilename directive.

SSLCachePath
Applicable when all of the following conditions are true:
- Platform is not Windows.
- SSL is enabled.
- SSLCacheDisable directive is not configured.
- bin/apachectl has been modified to specify a different -d flag, or bin/apachectl is launched with an explicit -d flag.
- The directory specified by the -d flag does not contain the file bin/sidd.
See the information on the SSLCachePath directive for Apache HTTP Server. See information on the SSLCachePath directive.
Other optional directives that specify a file path, like logging or tracing.
Ensure that no more than one IHS instance has the fast response cache accelerator (FRCA), or AFPA, enabled.

Note: FRCA/AFPA has been deprecated starting with V7.0 and its use is discouraged. There is no support for Windows Vista, Windows 2008, or any later Windows operating systems.
Start or stop the IHS server instance.
- Use these commands to start and stop IHS:
```
# cd /install_dir
# bin/apachectl -k start -f conf/this_instance.conf
# bin/apachectl -k stop  -f conf/this_instance.conf
```
  Alternatively, you can create a copy of apachectl for each instance, and update the commands in each copy to include "-f conf/this_instance.conf".
- Use these commands to setup a new instance:
```
cd \install_dir
bin\Apache.exe -f conf/this_instance.conf -k install -n IHS-this_instance
```
  Choose one of these commands to start and stop IHS:
  - Use this command:
```
net start IHS-this_instance
```
  - Use this command:
```
cd \install_dir
bin\Apache.exe -k install -n IHS-this_instance.conf
```
  - Find IHS-this_instance in the Services interface for Microsoft Windows.
See the topic on starting and stopping IBM HTTP Server for more information.