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Migrating and upgrading
You can upgrade to the 14.10 release of HCL Informix® or migrate from other database servers to Informix. Upgrading is an in-place migration method that uses your existing hardware and operating system software. Some changes to the Informix database server can affect upgrading from a previous release.
Migrating Informix® database systems
The Informix® Migration Guide describes how to move data manually between databases, servers, and computers.
Data migration utilities
The onunload and onload utilities
The onunload and onload utilities provide the fastest way to move data between computers that use the same database server on the same platform.
Guidelines for when to use the onunload and onload utilities
You can use onunload and onload only when certain conditions are met.

Migrating and upgrading
You can upgrade to the 14.10 release of HCL Informix® or migrate from other database servers to Informix. Upgrading is an in-place migration method that uses your existing hardware and operating system software. Some changes to the Informix database server can affect upgrading from a previous release.
- Migrating Informix® database systems
  The Informix® Migration Guide describes how to move data manually between databases, servers, and computers.
  - Overview of migration
  - Migration to and reversion from 14.10
  - Migration of data between database servers
  - Data migration utilities
    - External tables
      External tables are a fast and versatile method for moving data between database servers. External tables are the fastest method for loading data into a RAW table with no indexes.
    - The dbexport and dbimport utilities
      The dbexport and dbimport utilities import and export a database and its schema to disk or tape.
    - The dbload utility
      The dbload utility loads data into databases or tables that Informix® products created. It transfers data from one or more text files into one or more existing tables.
    - The dbschema utility
      The dbschema utility displays the SQL statements (the schema) that are necessary to replicate database objects.
    - The LOAD and UNLOAD statements
      You can use the SQL LOAD and UNLOAD statements to move data. The LOAD statement is moderately fast and easy to use, but it only accepts specified data formats. You usually use the LOAD statement with data that is prepared with an UNLOAD statement.
    - The onunload and onload utilities
      The onunload and onload utilities provide the fastest way to move data between computers that use the same database server on the same platform.
      - Guidelines for when to use the onunload and onload utilities
        You can use onunload and onload only when certain conditions are met.
      - Requirements for using the onload and onunload utilities
        The onload and onunload utilities have limitations. You can use these utilities only to move data between database servers of the same version on the same operating system. You cannot modify the database schema, logging must be turned off, and the utilities can be difficult to use.
      - How the onunload and onload utilities work
        The onunload utility, which unloads data from a database, writes a database or table into a file on tape or disk. The onload utility loads data that was created with the onunload command into the database server.
      - Syntax of the onunload command
        The onunload command unloads data from a database and writes a database or table into a file on tape or disk.
      - Logging mode
        The onunload utility does not preserve the logging mode of a database. After you load the database with onload, you can make a database ANSI compliant or add logging.
      - Syntax of the onload command
        The onload command loads data that was created with the onunload command into the database server.
      - Moving a database between computers with the onunload and onload utilities
        You can use the onunload and onload utilities to move a complete database from one computer to another.
      - Moving a table between computers with the onunload and onload utilities
        You can use the onunload and onload utilities to move a table from one computer to another.
      - Moving a table between dbspaces with the onunload and onload utilities
        You can use the onunload and onload utilities to move a table from one dbspace to another dbspace on the same computer.
    - The onmode utility reversion option
      You use the -b option of the onmode utility to revert to the older database server from which you converted.
    - The onrestorept utility
      You can use the onrestorept utility to restore the database server back to the state that it was in just before the start of the failed upgrade.

Guidelines for when to use the onunload and onload utilities

You can use onunload and onload only when certain conditions are met.

You can use only onunload and onload if your answer to each of the following questions is yes. If your answer is no, you cannot use onunload and onload.


Use onunload and onload only if your answer to each question is yes	My answer
Is the target database server on the same hardware platform?
Do you want to move to another database server of the same version?
Do you want to keep the existing database schema without modifying it?
Do you want to move an entire database or an entire table?
Are the page images compatible?
Are the numeric representations the same?

When you cannot use the onunload and onload utilities

Because the data is written in page-sized units, you cannot use onunload and onload to move data between UNIX™ or Linux™ and Windows™ because they use different page sizes. For example, the page size is 2 KB on some UNIX™ systems and 4 KB on Windows™.

Additionally, you cannot use onunload and onload:

To move data between GLS and non-GLS databases.
To move compressed data from one database to another.
You must uncompress data in compressed tables and fragments before you use the onload and onunload utilities.
To move external tables or databases that contain external tables.
You must drop all the external tables before you use the onunload utility.
To move tables and databases that contain extended or smart-large-object data types