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Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
System administration
These topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL Informix® database servers.
Administrator's Guide
The Informix® Administrator's Guide provides the information required to administer HCL Informix.
High availability and scalability
A successful production environment requires database systems that are always available, with minimal if any planned outages, and that can be scaled quickly and easily as business requirements change.
Cluster failover, redirection, and restoration
To maintain availability, you must plan for the failover of primary servers, redirecting client connections from unavailable servers, and restoring the cluster to its original configuration after a failure.
Redirection and connectivity for data-replication clients
When any server in a high-availability cluster becomes unavailable, any client connections to it should be redirected to an available server. The best way to handle connection redirection is to use Connection Manager to automatically reconnect client connections to the servers that you specify in service level agreements. Alternatively, you can control connection redirection with environment variables or connection information.
Redirecting clients with the connectivity information
You can redirect client connections to the new primary server by using sqlhosts information.

Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
- System administration
  These topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL Informix® database servers.
  - List of utilities
    HCL Informix® includes utilities and applications that you can use to perform administrative tasks and capture information about configuration and performance.
  - Administrator's Guide
    The Informix® Administrator's Guide provides the information required to administer HCL Informix.
    - The database server
    - Disk, memory, and process management
    - Logging and log administration
    - Fault tolerance
    - High availability and scalability
      A successful production environment requires database systems that are always available, with minimal if any planned outages, and that can be scaled quickly and easily as business requirements change.
      - Strategies for high availability and scalability
        HCL Informix® database software can be customized to create the appropriate high availability and scalability solution to match your business goals and environment.
      - High-availability cluster configuration
      - Connection management through the Connection Manager
        Connection Managers can control automatic failover for high-availability clusters, monitor client connections and direct requests to appropriate database servers, act as proxy servers and handle client/server communication, and prioritize connections between application servers and the primary server of a high-availability cluster. Connection Managers support high-availability clusters, replicate sets, server sets, and grids.
      - Cluster failover, redirection, and restoration
        To maintain availability, you must plan for the failover of primary servers, redirecting client connections from unavailable servers, and restoring the cluster to its original configuration after a failure.
        Failover configuration for high-availability clusters
        A failure in a high-availability cluster means that one of the servers is no longer available. If a primary server fails, you must promote a secondary server to the role of primary server. Connection Managers can be configured to perform automatic failover.
        Redirection and connectivity for data-replication clients
        When any server in a high-availability cluster becomes unavailable, any client connections to it should be redirected to an available server. The best way to handle connection redirection is to use Connection Manager to automatically reconnect client connections to the servers that you specify in service level agreements. Alternatively, you can control connection redirection with environment variables or connection information.
        Redirecting clients automatically with the DBPATH environment variable
        You can use the DBPATH environment variable in applications to redirect connections.
        Redirecting clients with the connectivity information
        You can redirect client connections to the new primary server by using sqlhosts information.
        Changing client connectivity information
        To use the connectivity information to redirect clients, you must change the connectivity information for the clients and change other connectivity files, if necessary.
        Connecting to the database server
        After the administrator changes the connectivity information and other connectivity files (if required), clients connect to the database server to which the administrator redirects them when they issue their next CONNECT statement.
        Automatic redirection with server groups
        Redirecting clients with the INFORMIXSERVER environment variable
        The INFORMIXSERVER environment variable redirection method can be used when an application does not explicitly specify a database server in the CONNECT statement, so that the client connects to the database server that the INFORMIXSERVER environment variable specifies.
        Redirecting clients with application code
        If you use the DBPATH environment variable or connectivity information to redirect connections, you can include in your clients a routine that handles errors when clients encounter a cluster failure. The routine can call another function that contains a loop that tries repeatedly to connect to the other database server in the cluster. This routine redirects clients without requiring the user to exit the application and restart it.
        Comparison of redirection methods
        The different redirection methods have different requirements.
        Recover HDR and RS clusters after failure
        When you restore the HDR or RS cluster back to the original configuration, you might need to restore critical media, as well as restart and configure servers in the cluster.
        Recovering a shared-disk cluster after data is damaged
        If a shared-disk cluster fails, you must perform a restore of affected dbspaces. The type of restore that you need to perform depends on whether critical data is damaged.
        Recovering an SD cluster after the secondary server became the primary server
        If a secondary server in an SD cluster became the primary server after the original primary server failed, you can use a script to reestablish the original primary and convert the current primary server back to a secondary server.
    - Distributed data
    - Overview of automatic monitoring and corrective actions
      You can use the SQL administration API, the Scheduler, and drill-down queries to manage automatic maintenance, monitoring, and administrative tasks.
  - Administrator's Reference
    The Informix® Administrator's Reference includes comprehensive descriptions of HCL Informix configuration parameters, the system-monitoring interface (SMI) tables in the sysmaster database, the syntax of database server utilities such as onmode and onstat, logical-log records, disk structures, event alarms, and unnumbered error messages.
  - DB-Access User's Guide
    The Informix® DB-Access User's Guide describes how to use the DB-Access utility to access, modify, and retrieve information from Informix database servers.
  - High-Performance Loader User's Guide
    The describes how to use the HCL Informix® to load and unload large quantities of data efficiently to or from Informix databases.
  - Performance Guide
    The Informix® Performance Guide describes how to configure and operate your HCL Informix database server to improve overall system throughput and to improve the performance of SQL queries.
  - SNMP Subagent Guide
    The describes the Simple Network Management Protocol (SNMP) and the software that you need to use SNMP to monitor and manage HCL Informix® database servers and databases.
  - InformixHQ Guide
    InformixHQ is a modern web console for visualizing, monitoring, and managing your Informix server instances. It is purpose built for ease-of-use, scaling out, and optimizing DevOps needs. It provides critical performance management capabilities, monitoring how key performance metrics are changing over time and tracking how efficiently Informix is running your workload even when you’ve stepped away from your screen. Its monitoring system feeds directly into a customizable alerting system so you can be immediately alerted via email, Twilio, or PagerDuty whenever an issue occurs on one of your Informix database server instances. InformixHQ is designed to be scalable to efficiently manage and monitor as many Informix database server instances as you need. Moreover, it's a tool that can be shared by the DBAs, the app developers, the ops engineers, and management and accessed from any desktop, laptop, or mobile device. InformixHQ is the centralized hub for graphical monitoring, alerting, and administration of your Informix database servers.
- Backup and Restore Guide
  The Informix® Backup and Restore Guide describes how to use the Informix ON-Bar and ontape utilities to back up and restore database server data. These utilities enable you to recover your databases after data is lost or becomes corrupted due to hardware or software failure or accident.
- Enterprise Replication
  The HCL® Informix® Enterprise Replication Guide describes the concepts of data replication using Informix Enterprise Replication, including how to design your replication system, as well as administer and manage data replication throughout your enterprise.

Redirecting clients with the connectivity information

You can redirect client connections to the new primary server by using sqlhosts information.

The connectivity information-redirection method relies on the fact that when an application connects to a database server, it uses the connectivity information to find that database server.

If one of the database servers in a replication pair is unusable, an administrator can change the definition of the unavailable database server in the connectivity information. As described in Changing client connectivity information, the fields of the unavailable database server (except for the dbservername field) are changed to point to the remaining database server in the replication pair.

Because the connectivity information is read when a CONNECT statement is issued, applications might be required to restart for redirection to occur. Applications can contain code that tests whether a connection failed and that issues a reconnect statement, if necessary. If a connection failed, redirection is automatic, and you are not required to restart applications for redirection to occur.

Applications can use the following connectivity statements to support this method of redirection:

CONNECT TO database@dbserver
CONNECT TO @dbserver

Applications can also use the following connectivity statements, provided that the INFORMIXSERVER environment variable always remains set to the same database server name and the DBPATH environment variable is not set:

CONNECT TO DEFAULT
CONNECT TO database

On UNIX™, the INFORMIXSQLHOSTS environment variable specifies the full path name and file name of the connection information in $INFORMIXDIR/etc/sqlhosts. For more information about INFORMIXSQLHOSTS, see the Informix® Guide to SQL: Reference.

On Windows™, the connectivity information is in a key in the Windows™ registry.