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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.
Disk, memory, and process management
Data storage
The database server uses physical units of storage to allocate disk space. It stores data in logical units. Unlike the logical units of storage whose size fluctuates, each of the physical units has a fixed or assigned size that is determined by the disk architecture.
Sbspaces
An sbspace is a logical storage unit composed of one or more chunks that store smart large objects.
Storage characteristics of sbspaces
As the database server administrator, you can use the system default values for these storage characteristics, or you can specify them in the -Df tags when you create the sbspace with onspaces -c. You can change these sbspace characteristics with the onspaces -ch option.
Extent sizes for sbspaces
An extent in an sbspace consists of a collection of contiguous pages that store smart large object data.

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
      - Virtual processors and threads
        These topics describe virtual processors, explain how threads run within the virtual processors, and explain how the database server uses virtual processors and threads to improve performance.
      - Manage virtual processors
        These topics describe how to set the configuration parameters that affect database server virtual processors, and how to start and stop virtual processors.
      - Shared memory
        These topics describe the content of database server shared memory, the factors that determine the sizes of shared-memory areas, and how data moves into and out of shared memory.
      - Manage shared memory
      - Data storage
        The database server uses physical units of storage to allocate disk space. It stores data in logical units. Unlike the logical units of storage whose size fluctuates, each of the physical units has a fixed or assigned size that is determined by the disk architecture.
        Chunks
        A chunk is the largest unit of physical disk dedicated to database server data storage.
        Pages
        A page is the physical unit of disk storage that the database server uses to read from and write to Informix® databases.
        Blobpages
        A blobpage is the unit of disk-space allocation that the database server uses to store simple large objects (TEXT or BYTE data) within a blobspace.
        Sbpages
        An sbpage is the type of page that the database server uses to store smart large objects within an sbspace. Unlike blobpages, sbpages are not configurable. An sbpage is the same size as the database server page, which is usually 2 KB on UNIX™ and 4 KB on Windows™.
        Extents
        An extent consists of a collection of contiguous pages that store data for a given table.
        Dbspaces
        A dbspace is a logical unit that can contain between 1 and 32,766 chunks. The database server uses the dbspace to store databases and tables. Place databases, tables, logical-log files, and the physical log in dbspaces.
        Blobspaces
        A blobspace is a logical storage unit composed of one or more chunks that store only TEXT and BYTE data.
        Sbspaces
        An sbspace is a logical storage unit composed of one or more chunks that store smart large objects.
        Advantages of using sbspaces
        Sbspaces have advantages over blobspaces.
        Sbspaces and Enterprise Replication
        Before you define a replication server for Enterprise Replication, you must create an sbspace. Enterprise Replication spools the replicated data to smart large objects.
        Metadata, user data, and reserved area
        As with blobspaces and dbspaces, when you create an sbspace, you assign to it one or more chunks. The first chunk of an sbspace always has three areas.
        Control of where smart large object data is stored
        You specify the data type of a column when you create the table.
        Storage characteristics of sbspaces
        As the database server administrator, you can use the system default values for these storage characteristics, or you can specify them in the -Df tags when you create the sbspace with onspaces -c. You can change these sbspace characteristics with the onspaces -ch option.
        Extent sizes for sbspaces
        An extent in an sbspace consists of a collection of contiguous pages that store smart large object data.
        Average smart-large-object size
        Smart large objects usually vary in length. You can provide an average size of your smart large objects to calculate space for an sbspace.
        Buffering mode
        When you create an sbspace, the default buffering mode is on, which means to use the buffer pool in the resident portion of shared memory.
        Last-access time
        When you create an sbspace, you can specify whether the database server must keep the last time that the smart large object was read or updated with the ACCESSTIME tag of the onspaces -c -Df option.
        Lock mode
        When you create an sbspace, you can specify whether the database server locks the whole smart large object or a range of bytes within a smart large object with the LOCK_MODE tag of the onspaces -c -Df option.
        Logging
        When you create an sbspace, you can specify whether to turn on logging for the smart large objects.
        Levels of inheritance for sbspace characteristics
        The four levels of inheritance for sbspace characteristics are system, sbspace, column, and smart large objects. You can use the system default values for sbspace attributes, or override them for specific sbspaces, columns in a table, or smart large objects.
        More information about sbspaces
        There are various tasks related to using and managing sbspaces.
        Temporary sbspaces
        Use a temporary sbspace to store temporary smart large objects without metadata logging and user-data logging.
        Plogspace
        A plogspace is a logical storage unit that is composed of one chunk that stores the physical log. When the physical log is in the plogspace, the database server increases the size of the physical log as needed to improve performance.
        Extspaces
        An extspace is a logical name associated with an arbitrary string that signifies the location of external data. The resource that the extspace references depends on a user-defined access method for accessing its contents.
        Databases
        A database is a logical storage unit that contains tables and indexes. Each database also contains a system catalog that tracks information about many of the elements in the database, including tables, indexes, SPL routines, and integrity constraints.
        Tables
        In relational database systems, a table is a row of column headings together with zero or more rows of data values. The row of column headings identifies one or more columns and a data type for each column.
        Table types for Informix®
        You can create logging or nonlogging tables in a logging database on HCL Informix®. The two table types are STANDARD (logging tables) and RAW (nonlogging tables). The default standard table is like a table created in earlier versions without a special keyword specified. You can create either a STANDARD or RAW table and change tables from one type to another.
        Tblspaces
        Database server administrators sometimes must track disk use by a particular table. A tblspace contains all the disk space allocated to a given table or table fragment (if the table is fragmented). A separate tblspace contains the disk space allocated for the associated index.
        Table fragmentation and data storage
        The fragmentation feature gives you more control over where the database stores data. You are not limited to specifying the locations of individual tables and indexes. You can also specify the location of table and index fragments, which are different parts of a table or index that are on different storage spaces.
        Amount of disk space needed to store data
        To determine how much disk space you require, follow these steps:
        The storage pool
        Every instance of the database server has a storage pool. The storage pool contains information about the directories, cooked files, and raw devices that the server can use if necessary to automatically expand an existing dbspace, temporary dbspace, sbspace, temporary sbspace, or blobspace.
        Disk-layout guidelines
        The following goals are typical for efficient disk layout:
        Sample disk layouts
        When setting out to organize disk space, the database server administrator usually has one or more of the following objectives in mind:
        Logical-volume manager
        You can use the logical-volume manager (LVM) utility to manage your disk space through user-defined logical volumes.
      - Manage disk space
        You can use several utilities and tools to manage disk spaces and the data that the database server controls.
      - Moving data with external tables
        You can use external tables to load and unload database data.
      - Storage space encryption
        You can encrypt storage spaces (dbspaces, blobspaces and smart blobspaces) with Informix Dynamic Server. The data in encrypted storage spaces is unintelligible without the encryption key. Encrypting storage spaces is an effective way to protect sensitive information that is stored on disk.
    - 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.

Extent sizes for sbspaces

An extent in an sbspace consists of a collection of contiguous pages that store smart large object data.

The unit of allocation in an sbspace is an extent. The database server calculates the extent size for a smart large object from a set of heuristics, such as the number of bytes in a write operation. For example, if an operation asks to write 30 KB, the database server tries to allocate an extent the size of 30 KB.

Important: For most applications, you must use the values that the database server calculates for the extent size.

If you know the size of the smart large object, you can use one of the following functions to set the extent size. The database server allocates the entire smart large object as one extent (if an extent of that size is available in the chunk):

The DataBlade® API mi_lo_specset_estbytes() function
For more information about the DataBlade® API functions for smart large objects, see the Informix® DataBlade® API Function Reference.
The Informix® ESQL/C ifx_lo_specset_estbytes function
For more information about the Informix® ESQL/C functions for smart large objects, see the Informix® ESQL/C Programmer's Manual.

For information about tuning extent sizes, see smart large objects in the chapter on configuration effects on I/O utilization in your Informix® Performance Guide.