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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.
Syntax of the onload command
The onload command loads data that was created with the onunload command into the database server.
Exclusive locking during a load operation
During a load operation, the onload utility places an exclusive lock on the new database or table.

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.
        onload source parameters
        The onload command includes options for specifying information about the tape or file source.
        onload create options
        The onload command includes information that is used to recreate the database.
        Constraints that affect onload
        The onload utility performs faster than the dbimport, dbload, or LOAD methods. In exchange for this higher performance, onload has certain constraints.
        Logging during loading
        When you use the onload utility to create tables from an onunload input tape, onload can load information only into a database without logging. Thus, before you load a table into an existing, logged database, you must end logging for the database.
        Movement of simple large objects to a blobspace
        If you load a table that contains simple large objects stored in a blobspace, the onload utility asks you if you want to move them to another blobspace.
        Ownership and privileges
        When you load a new database, the user who runs the onload utility becomes the owner. Ownership within the database (tables, views, and indexes) remains the same as when the database was unloaded to tape with onunload.
        Exclusive locking during a load operation
        During a load operation, the onload utility places an exclusive lock on the new database or table.
      - 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.

Exclusive locking during a load operation

During a load operation, the onload utility places an exclusive lock on the new database or table.

Loading proceeds as a single transaction, and onload drops the new database or table if an error or system failure occurs.