Home
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.
The database server
Client/server communication
These topics explain the concepts and terms that you must understand in order to configure client/server communication.
Configuration parameters related to connectivity
Some of the configuration parameters in the onconfig file specify information related to connectivity.
Connection information set in the LIMITNUMSESSIONS configuration parameter
The LIMITNUMSESSIONS configuration parameter is an optional parameter that specifies the maximum number of sessions that you want connected to HCL Informix®. If you specify a maximum number, you can also specify whether you want Informix to print messages to the online.log file when the number of sessions approaches the maximum number.

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
      - Overview of database server configuration and administration
        After you install HCL Informix®, you configure the database server system and start administering the database server.
      - Client/server communication
        These topics explain the concepts and terms that you must understand in order to configure client/server communication.
        Client/server architecture
        Informix® products conform to the client/server software-design model.
        Connections that the database server supports
        The database server supports different types of connections with client application.
        Local connections
        A local connection is a connection between a client and the database server on the same computer.
        Communication support services
        Communication support services include connectivity-related services
        Connectivity files
        The connectivity files contain the information that enables client/server communication and enable a database server to communicate with another database server.
        The sqlhosts information
        The sqlhosts information contains connectivity information for each database server and definitions for groups. The database server looks up the connectivity information when you start the database server, when a client application connects to a database server, or when a database server connects to another database server.
        Informix® support for IPv6 addresses
        On all platforms, HCL Informix® recognizes Internet Protocol Version 6 (IPv6) addresses, which are 128 bits long, and Internet Protocol Version 4 (IPv4) addresses, which are 32 bits long.
        Configuration parameters related to connectivity
        Some of the configuration parameters in the onconfig file specify information related to connectivity.
        Connection information set in the DBSERVERNAME configuration parameter
        When a client application connects to a database server, it must specify the name for the database server. The sqlhosts information that is associated with the specified database server name describes the type of connection between the application and the database server.
        Connection information set in the DBSERVERALIASES configuration parameter
        The DBSERVERALIASES configuration parameter lets you assign additional dbserver names to the same database server.
        Connection information set in the LIMITNUMSESSIONS configuration parameter
        The LIMITNUMSESSIONS configuration parameter is an optional parameter that specifies the maximum number of sessions that you want connected to HCL Informix®. If you specify a maximum number, you can also specify whether you want Informix to print messages to the online.log file when the number of sessions approaches the maximum number.
        Connection information set in the NETTYPE configuration parameter
        The NETTYPE configuration parameter lets you adjust the number and type of virtual processors the database server uses for communication. Each type of network connection (for example, ipcshm or soctcp) can have a separate NETTYPE entry in the configuration file.
        Name service maximum retention time set in the NS_CACHE configuration parameter
        The NS_CACHE configuration parameter defines the maximum retention time for an individual entry in the host name/IP address cache, the service cache, the user cache, and the group cache. If you specify maximum retention times, the database server gets host, service, user, and group database server information from the cache.
        Connection information set in the NUMFDSERVERS configuration parameter
        For network connections on UNIX™, use the NUMFDSERVERS configuration parameter to specify the maximum number of poll threads to handle network connections migrating between Informix® virtual processors (VPs).
        Connection information set in the HA_ALIAS configuration parameter
        The HA_ALIAS configuration parameter defines a network alias that is used for server-to-server communication in a high-availability cluster. The specified network alias is also used by Connection Managers, the ifxclone utility, and onmode -d commands.
        Environment variables for network connections
        The INFORMIXCONTIME (connect time) and INFORMIXCONRETRY (connect retry) environment variables affect the behavior of the client when it is trying to connect to a database server. Use these environment variables to minimize connection errors caused by busy network traffic.
        Automatically terminating idle connections
        You can automatically terminate sessions with clients that have been idle for a specified time by enabling the idle_user_timeout Scheduler task.
        Distributed Relational Database Architecture™ (DRDA®) communications
        DRDA is a set of protocols that enables multiple database systems and application programs to work together.
        Examples of client/server configurations
        The next several sections show the correct sqlhosts entries for several client/server connections.
      - Database server initialization
        The database server requires both disk-space initialization and shared-memory initialization.
    - 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.
    - 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.

Connection information set in the LIMITNUMSESSIONS configuration parameter

The LIMITNUMSESSIONS configuration parameter is an optional parameter that specifies the maximum number of sessions that you want connected to HCL Informix®. If you specify a maximum number, you can also specify whether you want Informix® to print messages to the online.log file when the number of sessions approaches the maximum number.

Distributed queries against a server are counted against the limit.

You might be required to dynamically increase or temporarily turn off the LIMITNUMSESSIONS configuration parameter to allow administrative utilities to run if the database server is reaching the limit. Use onmode -wf or onmode -wm to dynamically increase or turn off LIMITNUMSESSIONS.

If the LIMITNUMSESSIONS configuration parameter is enabled and sessions are restricted because of this limit, both regular user threads and DBSA user threads connecting to any database count against the limit. However, a DBSA user is allowed to connect to the server even after the limit is reached.

The LIMITNUMSESSIONS configuration parameter is not intended to be used as a means to adhere to license agreements.

Example

The following example specifies that you want a maximum of 100 sessions to connect to the database server and you want to print a warning message when the number of connected sessions approaches 100: LIMITNUMSESSIONS 100,1