On Sat, 28 Apr 2007 02:33:52 +0800, Ron Hawkins <[EMAIL PROTECTED]> wrote:
>Mark and co, > >I've always been of the opinion that with the advent of Disk Arrays, DEFRAG >became useless. Disagree. That did nothing for fragmentation. That was always the primary purpose of defrag - not performance. Consolidating extents was just an extra benefit. It wasn't until large DASD and DFSMS changes came about (or using ISV products that have "STOPX37" functionality) that made DEFRAG pretty much obsolete. If extent consolidation is really what you want, FDR COMPAKTOR can do that part only without "defragging" the entire volume. >It has become one of the biggest waste of time and resources >that I come across in way too many shops. Agree. > >For performance, DEFRAG is going to provide almost nil improvement for >sequential, and less for random where the volume you just spent all that >time reorganizing is spread across 2, 4, 8, 16 or 32 spindles and sharing >those disks with 100s of other volumes. > Agree. I don't know of any shops that ever ran DEFRAG or FDR COMPAKTOR that claimed it was for "performance" reasons. But someone did mention that in this thread. >I agree it can help with space allocation, but I can think of a dozen better >ways to mitigate space problems than by thrashing your channels and disk >drives for a couple of hours every day. It's a great way to trash your >remote copy links. Yes, there are better ways. Taking advantage of the DFSMS changes are one example. Don't know if I can think of 11 others, but there are others. Mark -- Mark Zelden Sr. Software and Systems Architect - z/OS Team Lead Zurich North America / Farmers Insurance Group: G-ITO mailto:[EMAIL PROTECTED] z/OS and OS390 expert at http://searchDataCenter.com/ateExperts/ Systems Programming expert at http://expertanswercenter.techtarget.com/ Mark's MVS Utilities: http://home.flash.net/~mzelden/mvsutil.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
