For traditional z/OS IO, on volumes larger than mod -3 I would prefer PAV (either DYNAMIC or HIPER).
IO is queued on the UCB. If the OS thinks the volume is busy, the IO is queued without even being attempted, IIRC. Ignoring the back end of the DASD device, you now have IO that would have been directed to 3 (or more) "actuators" being directed to 1. This will increase IO queueing. You *might* be able to get acceptable performance from a mod-9 with some judicious dataset placement, (hard to do in the days of SMS). Anything larger, I would insist on PAV. Not sure about the IO characteristics of the ZFS. HTH, <snip> We area also around here (i.e. convert 3390-3 or 3390-9 to 3390-27), my question is about the performance. Our DS6800 has no PAV, but we have a large number multivolume extended ZFS datasets. From the handling, backup etc, it would be better to have a 3390-27, but from performance point of view ? </snip> ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
