I have managed to recreate the problem. I will open a PMR and I will check with the developer why he is doing what he is. A cobol program reads input and then opens file (disp=mod) writes record and then closes file (50k times)
The following are the results of my tests: Open file write 50k records close file - file size 30 tracks less than a second CPU 50k times on a non extended file open write close - file size 600 tracks 3 minutes CPU 50k times on an extended file open write close - file size 23000 tracks 8 minutes CPU (catalog address space doing high i/o on vvds of disk being written to > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] > On Behalf Of Sheldon Davis > Sent: Wednesday, February 18, 2015 11:45 PM > To: [email protected] > Subject: High i/o rate and CPU usage by catalog after converting a set > of files > to extended and placing them on model 54's > > Hi > I am out of ideas. > We converted a set of sequential files to be extended and changed the > ACS routine to put the files on model 54's The following is what happened: > > 1. Jobs that allocated the files took more CPU and ran much longer. > 2. The catalog address space used about four times more CPU than usual > and did a huge amount of I/O on the disks that the batch job used to > allocate and > update the files. > > Thanks for any input ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
