John, If I recall correctly rewind and positioning are disconnect time. Run an RMF II background report at 5 second intervals and I expect you will see zero disconnect time most of the time, with occasional huge disconnect times during rewind and positioning.
Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of > John Kelly > Sent: Wednesday, February 03, 2010 10:51 AM > To: IBM-MAIN@bama.ua.edu > Subject: [IBM-MAIN] Tape drive disconnect time issue > > I have an old STK tape system ( ten 9840's in 3490 emulation mode inside a > 9740. Each drive ESCON point to point) , that will hopefully go away but > .... > > I have an issue with HSM dump running longer than expected. The problem > appears disconnect time. During the HSM dumps, we're using four drives for > two DumpClasses and most other stuff is stopped (some FTPs will come in). > No other tasks or LPAR is using any tape drive. Cpu is in the low 20% > range, DASD service time is around 4 ms and DASD rate is around 50 and > tape rate is around 600. > > One set of tape drives (1 tape for each of the two DumpClasses) has an RMF > average disconnect time of .84 and the other set of drives has an average > disconnect time of .06. This translates into a difference of 40k SIO in a > 15 minute interval. This disparity will last for almost an hour, then the > high disconnect time goes away (still using the same four tapes and > drives). SMF21 doesn't indicate any Erase Gaps or temporary errors which > I know causes high disconnect times. > > Jack Kelly > 202-502-2390 (Office) > > ---------------------------------------------------------------------- > 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
