Preparing to Configure High Availability Features

A description of the steps to complete before you configure High Availability features for Sybase CEP Engine.

Before you configure High Availability features for Sybase CEP Engine, complete the following steps:

In the c8-server.conf configuration file of every Sybase CEP Server in your cluster, designate whether you want Sybase CEP Server to act as a Manager, Container, or both Manager and Container. To do this, set the following preferences:
1. For every Sybase CEP Server in your cluster that you want to designate as a Container, set the "SybaseC8Server/Container/Enabled" preference to true:
```
<section name="SybaseC8/Server">
		...
		<section name="Container">
  ...
  <preference name="Enabled" value="true"/>
```
2. For every Sybase CEP Server that is enabled as a Container, that you do not also want to enable as a Manager, set the "SybaseC8/Server/Manager/Enabled" preference to false :
```
<section name="SybaseC8/Server">
		...
		<section name="Manager">
  ...
  <preference name="Enabled" value="false"/>
```
3. For every Sybase CEP Server in your cluster that you want to enable as a Manager, set the "SybaseC8/Server/Manager/Enabled" preference to true:
```
<section name="SybaseC8/Server">
		...
		<section name="Manager">
  ...
  <preference name="Enabled" value="true"/>
```
4. For every Sybase CEP Server that is enabled as a Manager that you do not also want to enable as a Container, set the "SybaseC8/Server/Container/Enabled" preference to false:
```
<section name="SybaseC8/Server">
		...
		<section name="Container">
  ...
  <preference name="Enabled" value="false"/>
```
Write down the host name and IP address of every Sybase CEP Server in your cluster, and note whether each Sybase CEP Server is enabled as a Manager, Container, or both. For example:
```
alpha 10.10.10.97 Manager
	bravo 10.10.10.98 Container
	...
```
For machines that include multiple network cards and have multiple IP addresses, note both addresses.
Check the following preference settings in the c8-server.conf configuration file of every Sybase CEP Server in your cluster. You will find some of these settings already set appropriately by the installation process, but will need to change others manually.
1. Set the "SybaseC8/Server/Common/Hostname" preference to the host name you wrote down in Step 2. For example:
```
<section name="SybaseC8/Server">
		<section name="Common">
   
   <preference name="Hostname">alpha</preference>
```
2. Set the "SybaseC8/Server/Common/ListenTo" preference to the IP address or host name on which you want the Sybase CEP Server to "listen". The default setting for this preference is 0.0.0.0, which indicates that Sybase CEP Server should listen to all available IP addresses:
```
<section name="SybaseC8/Server">
		<section name="Common">
   ...
   
   <preference name="ListenTo">0.0.0.0</preference>
```
  Some computers have multiple network cards, and, consequently, multiple IP addresses. If you want to limit the addresses to which Sybase CEP Server listens, list the addresses, or their associated host names here, instead of 0.0.0.0. If you are listing multiple addresses or host names, separate the entries by commas, for example:
```
<section name="SybaseC8/Server">                          <section name="Common">
   ...
   
   <preference name="ListenTo">
      12.13.14.15, 12.13.200.1</preference>
```
3. If more than one Sybase CEP Server uses the same host name or IP address, set each Sybase CEP Server to use a different port number, as shown in the next step. However, two Managers that use the same host name or IP address cannot both be part of a High Availability cluster, since all Managers in such a cluster must have the same port number.
4. Set the "SybaseC8/Server/Common/Port" preference to the port number you want each Sybase CEP Server to use, for example:
```
<section name="SybaseC8/Server">
		<section name="Common">
   ...
   
   <preference name="Port">6789</preference>
```

If you plan to configure the Manager failover High Availability, set the port for all Managers in your intended cluster to the same port number.

If any of the Sybase CEP Servers in your cluster are running on the same machine, set the "SybaseC8/Logging/LogWriters/FileLogger/Filename" preference to a unique file name for that machine, to ensure that each Sybase CEP Server has its own log file.
For example:
```
<section name="SybaseC8/Logging/LogWriters">
   ...
   <section name="FileLogger">
     ...
     <preference name="Filename">
     C:\ProgramFiles\SybaseC8\Server\logs\Container1.log
     </preference>
```
If you plan on configuring the Manager failover High Availability features (in which multiple Sybase CEP Servers are configured as Managers, though only one of these is active at a time) create a conf and storage directory, as explained here.

(If you plan on using only one Manager in your Sybase CEP Server cluster, and do not plan on enabling Manager failover, you can skip this step.)
1. Create a directory which all Managers are able to read and to which all of them will be able to write.
  
  If the Managers are running on different machines, all the machines must be able to connect to the shared directory.
2. Create two shared subdirectories named conf and storage under the shared directory you created in the previous step.
  
  For example, if the shared directory is C:\public\shared\home\C8MgrShared, the two subdirectories should be: C:\public\shared\home\C8MgrShared\conf and C:\public\shared\home\C8MgrShared\storage.
3. Write down the names of these directories.
  
  The Managers use these directories to communicate with one another.
Create a shared storage directory accessible to all the Containers in your cluster.

This directory may be the same as the storage directory you created in the previous step, or you may create separate storage directories for your Containers. This directory will be used by Containers to store data and prevent data loss during Container failover.
If you plan on configuring the Manager failover High Availability features, write down the following information about your DNS system.

(If you plan on using only one Manager with your Sybase CEP Server cluster, and do not plan on enabling Manager failover, you can skip this step.)
1. Write down the name of your DNS Server.
  For example:
```
DNSServ1
```
2. Write down the IP address of your DNS.
  For example:
```
10.10.10.254
```
3. Write down the DNS zone for your Managers.
  For example:
```
myzone.myco.com
```
4. Create and write down the generic host name alias that will be used to access the primary Manager, as explained in "Configuring Managers for Manager or Container High Availability".
  For example:
```
C8MgrShared
```
Make sure that the clocks of all computers included in your Sybase CEP Server cluster remain synchronized - for example, by using Network Time Protocol (NTP).