J, This is what Pat describes as "SIBLING PEND" and it is easy to spot the symptom because it shows up as Disconnect Time.
I sure IBM and EMC have something like HDS's Performance Monitor. It's a GUI with exportable data that you can use to monitor skewed activity across the parity groups that lead to the elongated seek affect that you describe. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of > J Ellis > Sent: Thursday, July 29, 2010 4:47 AM > To: IBM-MAIN@bama.ua.edu > Subject: Re: [IBM-MAIN] Any ROT for DASD Response time > > also, as some very wise people on this list and other lists/papers have > pointed out "Know thy data" some of our worst dasd response time issues were > eliminated by simply looking at the logical volume placement and the data > sets there on. Moving some DB2 indexes into different array groups and/or > off logical volumes that were splattered out towards the middle of the small > spinning back end dasd can make a great deal of difference (know your chunk > sizes, how the chunks are spread across the disks in the arrays, etc...). > RAID technology (at least yet) doesn't make up for bad placement of storage > group volumes and the data sets on them. As others pointed out, research Dr. > Artis papers on the subject--just my opinion and experience. > (Because we've always done it this way *BANG*)---Running HSM migration > management/space release-along with compactor jobs on different lpar in the > plex- on logical volumes that were on the front of the disks in the arrays > absolutely killed the hot indexes that were in the middle of the disks in > the same array. > > ---------------------------------------------------------------------- > 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
