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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.
Fault tolerance
Consistency checking
Deal with corruption
Fix I/O errors on a chunk

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
      - Mirroring
      - Using mirroring
      - Consistency checking
        Perform periodic consistency checking
        Deal with corruption
        Find symptoms of corruption
        You can find information about corruption several different ways.
        Fix index corruption
        Fix I/O errors on a chunk
        Collect diagnostic information
        Disable I/O errors
        Monitor the database server for disabling I/O errors
    - 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.

Fix I/O errors on a chunk

If an I/O error occurs during the database server operation, the status of the chunk on which the error occurred changes to down.

If a chunk is down, the onstat -d display shows the chunk status as PD- for a primary chunk and MD- for a mirror chunk. For an example of onstat -d output, see the Informix® Administrator's Reference.

In addition, the message log lists a message with the location of the error and a suggested solution. The listed solution is a possible fix, but does not always correct the problem.

If the down chunk is mirrored, the database server continues to operate using the mirror chunk. Use operating-system utilities to determine what is wrong with the down chunk and correct the problem. You must then direct the database server to restore mirror chunk data.

For information about recovering a mirror chunk, see Recover a mirror chunk.

If the down chunk is not mirrored and contains logical-log files, the physical log, or the root dbspace, the database server immediately initiates a stop action. Otherwise, the database server can continue to operate but cannot write to or read from the down chunk or any other chunks in the dbspace of that chunk. You must take steps to determine why the I/O error occurred, correct the problem, and restore the dbspace from a backup.

If you take the database server to offline mode when a chunk is marked as down (D), you can restart the database server, provided that the chunk marked as down does not contain critical data (logical-log files, the physical log, or the root dbspace).