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
