And if the buffer page is paged out to SCM, it should be faster to read it from SCM than from the DB2 data set. But if it is paged out to a page data set, it might be faster to read it from the DB2 data set, because DB2 (via Media Manager) uses zHPF, but z/OS has not been enhanced to use zHPF for page data sets.
Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY > 30 years ago this type of logic, to reread from DASD rather than demand > page-in a buffer page, *might* have made sense, when the I/O bandwidth > to the paging subsystem was limited based on the number of page datasets > and a demand page rate of 30-100 pages a second was common to see. But > the world has changed and it would not make sense to do it today. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
