Ted, I'm eating some humble pie while typing this.
I found an old article by Cheryl Watson published in August 1988 that described IO Service Units, I presume with IOSERV=TIME, as "1 IO Service Unit = 8.32msec of connect time (about 1/2 revolution of most DASD devices)." Being 1988 the DASD would have been 3380 which spun at 3600 RPM, which is an average latency of 8 1/3 msec. 3390s spun at 4200 RPM. 8.32 msec does divide evenly by 128 microseconds (128 * 6500 = 832000). I would be surprised if the proximity to average latency is anything more than a coincidence though. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of > Ted MacNEIL > Sent: Thursday, August 13, 2009 7:23 PM > To: [email protected] > Subject: Re: [IBM-MAIN] Degraded I/O performance in 1.10? > > >Ted, > > >I like to see the documentation. The Channel measurement block records > connect time and SRM in turn converts that to IO service units. >Are you > saying that 8.3ms was equivalent to 1 IO service Unit? > > Gotta look over 20 years ago. > > IOSRV=COUNT > IOSRV=TIME > > was an option, a long time ago. > I believe XA, but (as always) I could be wrong. > And, back then, it was documented as 8.3ms. > > Or was it IOSRVC? > > - > Too busy driving to stop for gas! > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] 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 [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
