I'll let you talk to IBM, since I don't do I/O performance measurements any more. I believe their number was perfectly correct at one time, but not now (see my post in reply to Ron Hawkins for details). If I were doing I/O performance measurement and tuning today, I would most definitely not use that number. Since you are using the number, you should verify its accuracy and, if not accurate any more, ask IBM yourself or else find a more modern analysis of average I/O service time.
Bill Fairchild Software Developer Rocket Software 275 Grove Street * Newton, MA 02466-2272 * USA Tel: +1.617.614.4503 * Mobile: +1.508.341.1715 Email: bi...@mainstar.com Web: www.rocketsoftware.com -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Ted MacNEIL Sent: Thursday, August 13, 2009 6:52 PM To: IBM-MAIN@bama.ua.edu Subject: Re: Degraded I/O performance in 1.10? >It was probably a good value to use aeons ago when it took a real SLED 3390 >16.67 ms. to spin around once, so 8.3 ms. was 1/2 revolution. >Today, >however, is aeons later as far as the hardware is concerned, especially >channel speed when delivering data from controller cache instead of straight >from the platter. Talk to IBM! I didn't make up the number. It's just what it is. - Too busy driving to stop for gas! ---------------------------------------------------------------------- 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
