Our MAXSYSTEM is set to 8 although there're only 6 LPAR's in the Sysplex. The IBM recommends false contention to be less than .5%. We consistently go over that threshold during our prime shift.
Our dirty little secret: We're running a dozen or so active ESDS' under RLS. I know IBM recommends against this but we're pretty much stuck due to the application's architecture. The best we might be able to do is change our application's "randomizer" to reduce cross-system/cross-CICS contention. File owning regions (FOR's) aren't an option due to availability concerns. Robert Crawford Mainframe Management United Services Automobile Association (210) 913-3822 “Moy glaz! YA ne dolzhen dobavlyat' v nego puding!” - Tolstoy Please send requests to mainframe management through our front door at go/mfmfrontdoor -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Attila Fogarasi Sent: Tuesday, January 11, 2022 4:22 PM To: [email protected] Subject: EXTERNAL: Re: RLS False Contention Statistics What is your MAXSYSTEMS value? There is a false lock contention penalty when your MAXSYSTEMS value exceeds 7 or 23. Of course your MAXSYSTEMS has to match the actual number of parallel sysplex members :) Also what is your false lock contention rate? 1% is typically acceptable though it really varies with your application structure. Ultimately it is an application design issue, and Db2/IMS do a much better job of concurrent data access. On Wed, Jan 12, 2022 at 2:19 AM Crawford, Robert C. < [email protected]> wrote: > All, > > I can't reconcile RLS lock structure false lock contention between the > various SMS statistics records. > > According to the type 42 subtype 17 we have a lot of false contention > (field SMF42HCC). However, our type 42 subtypes 15 (storage class > response > time) and 16 (dataset response time) false contention buckets are zero. > The only exception in the 16's and 17's are fields SMF42GUB and > SMF42FUB that record locks that hashed to the same entry, which I > thought was the definition of false contention. However, the > statistics in those fields are a little more than half than the false > contention reported in the subtype 15's. > > I have SMS dataset monitoring set up for both SMF and IGWDATA. > > We are feature level Z (don't ask) so all the statistics should be > below the line. > > Our lock structure is already 1G in size so I'd like to find the root > cause of the false contention before making it any bigger. > > Does anyone have some advice? > > Thanks. > > Robert Crawford > Mainframe Management > United Services Automobile Association > (210) 913-3822 > > "Moy glaz! YA ne dolzhen dobavlyat' v nego puding!" > - Tolstoy > Please send requests to mainframe management through our front door at > go/mfmfrontdoor< > https://urldefense.com/v3/__https://onc.jira.usaacloud.com/secure/Dash > board.jspa?selectPageId=15466__;!!GryZGb6B1VCs0SfC!TrpjUotsagny5EiQXOx > Ek8XLA34t_PRZ1cAAEi6zQn9KKZOwLw1z2wVKBGQ6eOWQPuE$ > > > > ---------------------------------------------------------------------- > 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 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
