Thanks for your responses. Ed/Adolph - the disks are net new - we have not started consolidating yet.
Ron - Cache disk ratio was my error - I meant cache hit ratio. The DB2 disks used until we started this experiment are all MOD-3 with hyperpav. I am not aware of cache partitioning - I will look into it. We currently have 3 MOD-27s and approx 190 MOD-3s with DB2. I am going to look into the Array Group activity monitor Another factor - DB@ I/O is low compared with our total IO profile Mike On Tue, Dec 29, 2009 at 8:41 AM, Ron Hawkins <ron.hawkins1...@sbcglobal.net>wrote: > Mike, > > > > What is "Cache Disk ratio?" > > > > Were you using PAV or HyperPAV on the smaller volumes where the DB2 > datasets > were previously allocated? > > > > I've benchmarked HDS storage from 9900 to USP-V and found no performance > differences due to the volume size formatted on the array group > (3390-3/9/27/54 and Custom volume Sizes). > > > > Have you checked the Array Group activity before and after the change to > 3390-27? You can do this with your Performance Manager software launched > from Storage Navigator. > > > > It's a common problem to end up with back-end IO spread over less spindles > during volume consolidation, such that you end up with a sibling pend > problem. Taking datasets spread over 50 or more array groups formatted as > 3390-3 or 3390-9 and allocating them on just a few array groups formatted > as > 3390-27 will often cause the problem you are seeing. > > > > Ron > > > > > -----Original Message----- > > > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On > Behalf Of > > > Mike Shorkend > > > Sent: Monday, December 28, 2009 10:58 AM > > > To: IBM-MAIN@bama.ua.edu > > > Subject: [IBM-MAIN] HDS/USP Model 27 DASD and DB2 > > > > > > Hello All, > > > We have started experimenting with MOD-27 disks on a USP600 box. > > > We have found that with DB2, response times have deteriorated > significantly. > > > We are seeing response times of more than 10ms on a fairly active disk. > > > Disconnect time accounts for about 90% of the time. Cache disk ratio has > > > gone down for these disks to less than 10%. > > > HYPERPAV is active - IOSQ time is zero. zHPF is not enabled. > > > > > > z/OS 1.9. DB2 V8. > > > > > > We have opened an issue with Hitachi. > > > Has anyone else experienced this in a similar configuration? > > > > > > 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 > -- Mike Shorkend m...@shorkend.com www.shorkend.com Tel: +972524208743 Fax: +97239772196 ---------------------------------------------------------------------- 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
