One crucial parameter: at what distance are the CFs? There must be a noticable difference between 5 usecs for an unduplexed local CF or a number of 150 usecs signals between CFs at 15 km distance.
Kees. -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Martin Packer Sent: 22 December, 2015 8:55 To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: [Bulk] Re: Coupling Facility Structure Re-sizing We're not going to BLANKET recommend System-Managed Duplexing for high-volume, high stringency structures such as LOCK1. SCA has little traffic. But I've seen MANY customers (including the one I worked with yesterday here in Istanbul) that successfully use it. And I support their use of it. Other customers: 1) Have a failure-isolated CF for such structures. Or 2) Take the risk of doing neither. I've seen all 3 architectures even in the past 6 months. And your local IBMer is normally willing to give their view, hopefully backed up by data and people who know what they're talking about. :-) Cheers, Martin Martin Packer, zChampion, Principal Systems Investigator, Worldwide Cloud & Systems Performance, IBM +44-7802-245-584 email: martin_pac...@uk.ibm.com Twitter / Facebook IDs: MartinPacker Blog: https://www.ibm.com/developerworks/mydeveloperworks/blogs/MartinPacker From: "Vernooij, CP (ITOPT1) - KLM" <kees.verno...@klm.com> To: IBM-MAIN@LISTSERV.UA.EDU Date: 22/12/2015 07:39 Subject: Re: [Bulk] Re: Coupling Facility Structure Re-sizing Sent by: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> Of course 'it depends'. At least on the distance between the CFs. Signals are delayed by 10 usec/km. The number of signals traveling for SMCFSD have indeed been optimized since the beginning, but it still makes a difference if the CF's are 1 or 15 kms apart. Our latest researches from this year is that IBM still does not recommend SMCFSD for Lock and SCA. What is your configuration? If a CEC fails, others DB2's in the group should do the recovery without delay. Did all your CECs and DB2s fail? Our experience is that a group-restart is very fast, at max. 2 - 3 minutes and that are also IBMs figures. Altogether, we still see advantages in not using SMCFSD for Lock and SCA. Why did you decide different? Kees. -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Skip Robinson Sent: 21 December, 2015 20:32 To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: [Bulk] Re: Coupling Facility Structure Re-sizing I'm talking from experience. The two hours-long CEC failures we had--most recently in the fall of 2014--took down all CICS and DB2 applications as well as three ICFs on the box that failed. The secondary 'penalty' box stayed up and kept live copies of structures so that after hardware repair, all LPARs--host and CF--came up with no recovery needed. In particular, no DB2 log processing, which is the worst case for recovery. As for processing overhead, that's why IBM delayed SMCFSD. We're as concerned with performance as any shop. Millions of CICS/DB2 transactions per hour. For DASD mirroring, we went with XRC (async) rather than PPRC (sync) for that reason. Today we see no visible delays from SMCFSD. This is predicated on having enough CF engines to do the job. As previously stated, beware of putting CF LPARs on hardware that's slower than the exploiters. Note that CF, ZIIP, and IFL engines run at full rated speed even on a box that's 'downsized' to run GP engines at less than maximum speed--to save software costs. That's why we're happy to put ICFs on otherwise slower penalty boxes. . . . J.O.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler The SHARE MVS Program Co-Manager 323-715-0595 Mobile jo.skip.robin...@att.net jo.skip.robin...@gmail.com > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] > On Behalf Of Vernooij, CP (ITOPT1) - KLM > Sent: Sunday, December 20, 2015 11:35 PM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: [Bulk] Re: Coupling Facility Structure Re-sizing > > Your last statement is far too general in my opinion. SMCFSD is not free: besides > memory, which indeed is cheap these days, it will cost performance, like PPRC > does. > So one must always make the decision about having high availability or high > performance. > Even without SMCFSD, Structure availability is very high. And in the rare event of > a CF failure (when was you last one?) each exploiter of CF Structures should be > able to recover from that failure. In my experience they all do, except MQ. > If you have a CF failure, the structures are recovered within seconds or minutes. > If you can't bear the recovery delay, you can use Duplexing. Besides that, if you > have a CF failure, what other problems do you have? Do you still need the zero > recovery delay then? > > Kees. > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] > On Behalf Of Skip Robinson > Sent: 19 December, 2015 5:57 > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Coupling Facility Structure Re-sizing > > Wow, I feel so ancient. In the History of the World Part II, there are two kinds of > duplexing. The late comer is System Managed Duplexing, which is provided by > z/OS - XCF - XES. The exploiter does not need to participate in SMD (my > acronym); he just reaps the benefits. But SMD for customer use was delayed for > quite a while because IBM could not get it working. (More history.) > > Meanwhile DB2 could not wait for SMD and developed their own duplexing > mechanism. Hence DB2/IRLM does not need/use SMD. I forgot that when I > mentioned DB2 recovery. So I recommend that DUPLEX be specified for all other > structures that need SMD. > > . > . > . > J.O.Skip Robinson > Southern California Edison Company > Electric Dragon Team Paddler > SHARE MVS Program Co-Manager > 626-302-7535 Office > 323-715-0595 Mobile > jo.skip.robin...@att.net > jo.skip.robin...@gmail.com > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] > On Behalf Of phil yogendran > Sent: Friday, December 18, 2015 12:19 PM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: [Bulk] Re: Coupling Facility Structure Re-sizing > > The increases recommended by the CF Sizer is marginal. Our structures in > production are generously sized and we have lots of storage in the new CFs so > that's not a concern. I will however lookout for messages as suggested. > > Most of our structures are duplexed. Some like the structure for the IRLM lock > are not. I have a note to investigate the product specific doc to understand this > better. > > I also need to check on the performance of CF links as we're going to ICB links > now. > > Thanks for the info. > > > > > On Fri, Dec 18, 2015 at 12:42 PM, Skip Robinson <jo.skip.robin...@att.net> > wrote: > > > In case you're curious, the parameters 'missing' from your old > > definitions were added over the years since the advent of coupling > > facility. The new parameters all have defaults such that they do not > > actually require specification, but using them may give you better > > control over structure sizes. Some additional points: > > > > -- At any time, the CF Sizer makes recommendations based on the latest > > hardware with the latest microcode. Newer hardware or newer microcode > > typically requires larger structures to accomplish the same work even > > with no changes to the exploiters. > > > > -- In my experience, CF Sizer makes very generous recommendations. > > Memory is cheaper now than ever, but watch out for gratuitous over > allocation. > > Especially on an external CF, you might be constrained. > > > > -- Several structures require that you input data to CF Sizer on how > > busy you expect the structure to be. For most, this has less to do > > with the number of sysplex members than the amount of data the > > structure has to handle. This is seldom easy to determine. Make your > > best SWAG and monitor the results. > > > > -- The worst case is when a structure is too small for the exploiter > > to initialize. I have not seen this for some time; maybe the big > > exploiters have been (re)designed to come up regardless. But watch for > > messages indicating that a structure needed more than the specified > > minimum size at the outset. > > > > -- A parameter you did not ask about is DUPLEX. Even if you have only > > one box for CF use, I recommend two CF LPARs on that box with > > duplexing for relevant structures. Better of course would be two > > boxes. The best thing about sysplex is its ability to survive > > disruptions. Over the years we have had two CEC failures. In both > > cases, the second CF allowed all applications to resume with zero data > > recovery efforts. Note that some structures do not require duplexing, notably > GRS. If a host dies, so do all of its enqueues. > > > > > > . > > . > > . > > J.O.Skip Robinson > > Southern California Edison Company > > Electric Dragon Team Paddler > > SHARE MVS Program Co-Manager > > 323-715-0595 Mobile > > jo.skip.robin...@att.net > > jo.skip.robin...@gmail.com > > > > -----Original Message----- > > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] > > On Behalf Of phil yogendran > > Sent: Friday, December 18, 2015 07:39 AM > > To: IBM-MAIN@LISTSERV.UA.EDU > > Subject: [Bulk] Re: Coupling Facility Structure Re-sizing > > > > Thank you all for your replies. I will take your suggestions into > > consideration going forward. We are in the process of upgrading from > > z10 - > > > z12 -> z13 over the next few months. The CF upgrade is a part of > > > this > > project. The CFs are going from 2097/E10 and 2098/E12 to 2817/M15. > > > > I expect to see better structure response with these changes and will > > be surprised to see anything otherwise. Will keep you posted. Thanks again. > > > > On Fri, Dec 18, 2015 at 8:16 AM, Richards, Robert B. < > > robert.richa...@opm.gov> wrote: > > > > > The archives probably have it, but simply put and if IIRC, there was > > > an old 9674 being used with z990s. Waiting on CF structure response > > > was horrific as compared to the speed of the z990 processor response. > > > > > > -----Original Message----- > > > From: IBM Mainframe Discussion List > > > [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Elardus Engelbrecht > > > Sent: Friday, December 18, 2015 7:55 AM > > > To: IBM-MAIN@LISTSERV.UA.EDU > > > Subject: Re: Coupling Facility Structure Re-sizing > > > > > > Richards, Robert B. wrote: > > > > > > >The last thing you want is for your CFs to be slower than the CPs. > > > >BTDTGTS > > > > > > Ouch. Could you be kind to tell us about it? Are there any manuals > > > stating that trouble? Any configuration changes to avoid? Or is it > > > about the sizes or quantity of LPARs involved? > > > > > > TIA! > > > > > > Groete / Greetings > > > Elardus Engelbrecht ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ******************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. 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