On 15 Mar 2016 07:55:41 -0700, in bit.listserv.ibm-main Mike Schwab wrote: >On our HSM MCDS, BCDS, etc, we have 0 for the secondary extent. >If we specified TRACK(50000 1) so we get 1 track as the Control Area, >1. How much would the Index size go up? 15X? >2. Wouldn't CAs be reused a lot more frequently, since you only have >to get 1 track empty instead of 15? >3. Which would be better for an end user? >4. How would throughput be affected?
I would definitely not go for this. With a good choice of data and index CI sizes, the indexes for a cylinder sized CA should fit in one index CI. For the size of the data set you should have no more than 3 index (2 plus the sequence set) levels. With a track size CA you will have at least 4 index levels. Clark Morris > >On Tue, Mar 15, 2016 at 6:07 AM, John Eells <ee...@us.ibm.com> wrote: >> Norbert Friemel wrote: >> <snip> >>> >>> >>> CA_RECLAIM? >>> http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/2.5.3.3 >> >> <snip> >> >> Norbert beat me to it (smile). The key to this being useful is that you >> have empty CAs to reclaim. One could have a pathological application that >> left one record per CA behind after deleting the rest, so that no CAs ever >> emptied out to be reclaimed, for example. Or, one could have an even *more* >> pathological application that wrote a lot of records into specific key >> ranges, deleted them all (causing reclaims) and then rewrote a lot of >> records into the same key ranges, causing CA reclaim/CA allocation thrashing >> to the detriment of performance. >> >> That said, it's very likely that using CA Reclaim will get you out of the >> reorg business, permanently, with no ill effects, for all of your KSDSs. CA >> Reclaim is available on all supported releases now, but I have heard of only >> one pathological application so far. Of course, it was one of ours here at >> IBM. (You can't make this stuff up.) >> >> -- >> John Eells >> IBM Poughkeepsie >> ee...@us.ibm.com >> >> >> ---------------------------------------------------------------------- >> For IBM-MAIN subscribe / signoff / archive access instructions, >> send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
