Perform Library Function codes

This topic describes the Perform Library Function (PLF) codes that can be returned when an IBM® TS7700 Grid operates attached to a physical library.

The PLF command is used to pass command and control information to a library manager through the controller that services the attached drive string. This command transfers an order-dependent number of data bytes, which contain an order code, common information, and order unique parameters. The order code specifies what operation is to be completed by the library manager.

Operations are either run immediately or queued by the library manager as an asynchronous operation. Immediate operations are completed before the ending status is presented. Asynchronous operations are completed after the ending status is presented and can result in the generation of a delayed response attention message.

Error conditions that are related to PLF commands can be detected either during execution of the PLF command or during execution of a resulting asynchronous operation. Errors that are detected during command execution are reported with ending status as a unit check and associated sense data, described by Error Recovery Action (ERA) codes. Errors that are detected during the execution of an asynchronous operation are reported through completion codes. They are presented in a delayed response message or through the presentation of unsolicited unit checks and/or unsolicited attention messages.