Michael, Check your HSM Activity log for msg. ADR035I, then check the Optimize value.
OPTIMIZE(4) will provide you with the least amount of physical I/O. Change the DUMPIO(n) in HSM parmlib if necessary. HTH, Dave O'Brien NIH Contractor ________________________________________ From: Michael R. Mayne [michael.ma...@hhsys.org] Sent: Wednesday, November 18, 2009 7:08 PM To: IBM-MAIN@bama.ua.edu Subject: Re: High CPU / channel ovhd w/3592 and DFDSS OK, I'll 'fess - the old tape subsystem is a 3490-A20 controller with 2 3490-B40 drive units. The old tape subsystem has hardware compression, as does the new. I'll check for software compression (never thought of it, actually), but I doubt that it's turned on. If it was, I'd expect CPU (on this box, which is a Uni) to be closer to 100% than 50%. Compression would also not explain why the CHPID utilization for the tapes is so high (and I think the CHPID utilization is directly related to the CPU overhead). Could I have them defined inefficiently somehow in my IOCDS? Am I doing bad things to tape performance with DFSMS DATACLAS or STORCLAS settings? I guess I won't know exactly what's wrong until it's fixed... Thanks. -Mike ---------------------------------------------------------------------- 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
