DASD Update Processing
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
When non-retentive data is written, ending status is presented to the channel when the data has been transferred from the channel to the cache. The non-retentive data is written to the disk device (DASD) when the non-retentive data becomes Least Recently Used (LRU). If the data never becomes Least Recently Used (e.g., data is frequently accessed), the data will never be written to the DASD. The user needs the ability to ensure that the data is on the DASD without causing a performance impact. With the Schedule DASD Update (SDU) option, all non-retentive data for the device is scheduled for destage (Write to DASD) as a background operation. Channel commands to the specific device are still allowed which enable the performance level to be maintained.