All, I recommend Lizette have a look at the papers "do you have one second response time" and with "Everything You Know is Wrong," and decide from empirical observation what a good response time is for the workload in question.
For example, if this is predominantly read CA-IDMS or IMS DEDB, workloads that have notoriously poor locality of reference because of key hashing, then one would expect response time to be in the 5-15ms range, depending on how busy spindles are and how the workload is short or long stroked. If this CICS/VSAM application with a heavy random write load, than with a 4KB CISZ it would perfectly reasonable to expect response time to be less than 0.5ms with near zero disconnect time if the workload has been laid out to avoid destage skew. However turn on synchronous remote copy over 200km and that 0.5ms will become more like 2ms. And we could chat for hours about the affect of busy Initiator and Target microprocessors on those long, chained IO that DFSORT and SYNCSORT like to do... It's IO elongation at its best (or worse as the case may be). So while one can come up with a rule of thumb for DASD response time, it does require some categorization of the IO generated by the workload, and an understanding of the underlying Disk topology that will process the IO before one settles on the right rule of thumb. It will probably be somewhere between what you want and what you are getting. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of > Ed Finnell > Sent: Wednesday, July 21, 2010 8:29 PM > To: IBM-MAIN@bama.ua.edu > Subject: Re: [IBM-MAIN] Any ROT for DASD Response time > > > In a message dated 7/21/2010 3:02:23 P.M. Central Daylight Time, > eamacn...@yahoo.ca writes: > > That, of course, is totally unrealistic. > > 2-5ms/IO is reasonable, IMO. > > > >> > The folks over at _www.perfassoc.com_ (http://www.perfassoc.com) do this > for a living. They got White Papers on different vendors and models. For $$$ > they'll help you more. SHARE and Redbooks are good trolling grounds. > > > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
