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.

The onload and onunload utilities have the following requirements:
  • The original database and the target database must be from the same version of the database server. You cannot use the onload and onunload utilities to move data from one version to another version.
  • You cannot use onload and onunload to move data between different types of database servers.
  • The onload command must have the same scope as the corresponding onunload command that unloaded the same table or tables that onload references. You cannot, for example, use onunload to unload an entire database, and then use onload to load only a subset of the tables from that database.
  • Do not use onload and onunload to move data if the database contains extended or smart-large-object data types.
  • Because the tape that onload reads contains binary data that is stored in disk-page-sized units, the computers where the original database resides (where you use onunload) and where the target database will reside (where you use onload) must have the same page size, the same representation of numeric data, the same byte alignment for structures and unions.
  • You cannot use onload and onunload to move data between non-GLS and GLS locales.
  • You cannot use onload and onunload on servers in high-availability clusters.
  • You cannot use onload and onunload if you compressed tables or fragments.

You can use onunload and onload to move data between databases if the NLS and GLS locales are identical.

If the page sizes are different, onload fails. If the alignment or numeric data types on the two computers are different (for example, with the most significant byte as last instead of first, or different float-type representations), the contents of the data page could be misinterpreted.