PPRC synchronous completes the I/O when the result is posted to the secondary dasd. PPRC asynchronous completes the I/O when the result is posted to the primary dasd. During busy times you might get multiple updates to a track before the last update is sent.
On Wed, Nov 30, 2022 at 2:33 AM Johnny Luo <[email protected]> wrote: > > Hi, > > Several months ago we conducted two tests on our system. In the first test, > when cics transaction rate reached 9000, response time deteriorated badly. > So we stopped the PPRC and repeated the test. As expected, we got very good > response time. > > Surprisingly, however, our transaction cpu time also decreased from 2.6ms > to 1.9ms. This goes beyond my knowledge and imagination. As I know, z/os > starts an io request to channel subsystem and then goes to process other > things. When that io is ready, channel subsystem will interrupt the cpu and > z/os gets to process the interruption. In the above process, I can see no > place where user program's cpu usage can be affected. Of course you'll get > better response time. > > Thanks. > > > Best Regards, > Johnny Luo > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
