7/6/2005 11:32 AM Tom Schmidt <[EMAIL PROTECTED]> wrote There is a more fundamental issue here: VSAM keeps its statistics records in KEY 8 storage in the address space's private area, ... Those statistics records can, and often are in the case of a storage overlay, subject to corruption and/or destruction because of that inherent lack of protection.
VSAM (and other access methods perhaps) needs to have a protected area for such apparently customer-important data as statistics. ... ... The problem with using interval accounting to try to anticipate the ABENDs ... ... 1) One can always do one's own interval accounting by opening and closing the file periodically. 2) In a prior life about a decade ago I remember that the control block containing at least some of the statistics was in CSA, where it was much less likely to be overlaid. With a CSA overlay the devil jumps much faster and higher and sooner and is easily detected. It may be that that control block was only in CSA when shroptns=3, which we used -- an option sane people don't use. The control block was small and could be easily be put in CSA always with minimal cost in these days of ubiquitous VSCR. 3) Don't "eyecatchers" act as effective canaries to know when an overlay has occurred? I know we used them extensively in the prior life to know when we were wounded but not yet informed thereof. 4) There has been much discussion of the desirability of "bad" statistics. If I am using "bad" statistics for billing, I can use reasonability checks to determine if the basis of the bill is bogus and eat the cost rather than offend the client. If I am decisioning with possibly "bad" statistics, I can adjust my algorithm to be tolerant. When I was trained as a physicist, accomodating error was a standard part of any measurement process. The conclusion can often be made using "bad" data, even if an automaton is doing the work. The first paper in Physical Review Letters (~1964 Penzias & Wilson) on the "big bang theory" showed a graph with very large error on the measurements. But in that case merely the order of magnitude of the data points allowed a conclusion to be drawn. Or as one could hear said in the 60's (when the first dinosaur ...) It doesn't take a weatherman to know which the wind is blowing. pup strolling down memory lane p.s. I think Mr Thomen is to be commended for his persistent patience. ----------------------------------------- The information contained in this communication (including any attachments hereto) is confidential and is intended solely for the personal and confidential use of the individual or entity to whom it is addressed. The information may also constitute a legally privileged confidential communication. If the reader of this message is not the intended recipient or an agent responsible for delivering it to the intended recipient, you are hereby notified that you have received this communication in error and that any review, dissemination, copying, or unauthorized use of this information, or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail, and delete the original message. Thank you ---------------------------------------------------------------------- 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
