DASD STORAGE BACK-UP USING OUT-OF-SEQUENCE WRITES

摘要

A back-up system. The back-up system sequences through DASD locations and stores the DASD data. The DASD records which DASD locations have been backed-up. The DASD concurrently receives and performs CPU activity including write transactions. If a write transaction is received that targets a DASD location that has not yet been backed up, the DASD backs up the data block at that target location, out of sequence. The DASD then resumes with sequencing through the DASD locations and concurrently performing normal CPU activity. The invention may be realized in a variety of system configurations. The inventive logic is preferably realized in the DASD, but may also be realized in the CPU.