Method Using Token and Token Table to Prevent I/O Operations to Selected Data Sets After Subsystem Failure
Original Publication Date: 1985-Aug-01
Included in the Prior Art Database: 2005-Feb-19
When a failure has occurred and a data processing subsystem is being restarted or the subsystem is transferred to a backup processor, I/O operations that were in progress for selected data sets are prevented from executing. The operations are later restarted in an orderly way that avoids damage that might otherwise occur to these data sets. The operating system maintains a table that has an entry for each of the selected data sets. Each entry has two fields, one that tells whether the entry is valid or invalid and one that has an identifying number. The identifying number of each entry is initially zero. When a data set is selected for I/O operations to be prevented, a previously invalid entry is assigned to the data set. The valid/invalid field is set to valid, and the identifying number is incremented.