Rex, It is based on an IO per hour rate for the page. Occasionally referencing a page, or thousands of pages will not cause the page(s) to be promoted from tier 3 unless the activity is prolonged or intense enough to change the IO/hour. There are both short and long term IO/hour measures that are weighted to influence promotion/demotion.
If cycle time is set appropriately and the activity is extreme enough the pages could start to be promoted within 30 minutes. Ron -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Pommier, Rex Sent: Tuesday, August 26, 2014 7:07 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: [Bulk] Re: [IBM-MAIN] [Bulk] Re: [IBM-MAIN] General question on moving DFHSM work from mix TAPE/DASD to More DASD Ron, One of your explanation paragraphs caught my attention so I'm asking out of curiosity, for my own benefit. <your paragraph> What I find important is there is no data transformation or recall latency: it is all transparent to the application. You have to read 12 months of General Ledger files or SMF data sets? The application simply reads them directly from whatever tier disk the pages happen to be on. You're not waiting 24 hours for data sets scattered all over myriad ML2 tapes to be recalled, you don't have to find redundant Primary space to store the recalled data sets, and there won't be any TMM thrash when they are migrated again by the next space management cycle. That process is transparent to z/OS in the way we thought the STK Iceberg would go. Of course all this dormant data remains replicated with TC and/or HUR while it is being shuffled around the backstore tiers in both sites - you're not moving any DFSMShsm traffic across the replication links. </your paragraph> The sentence where you said "the application simply reads them directly from whatever tier disk the pages happen to be on" intrigues me. Does the HDS scenario you are talking about here use some kind of algorithm to leave this kind of data on the level-3 spindles for a certain number of reads (or something else like that) or once the page is referenced does it work in the background to elevate the pages to higher performance tiers? Thanks, Rex The information contained in this message is confidential, protected from disclosure and may be legally privileged. If the reader of this message is not the intended recipient or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any disclosure, distribution, copying, or any action taken or action omitted in reliance on it, is strictly prohibited and may be unlawful. If you have received this communication in error, please notify us immediately by replying to this message and destroy the material in its entirety, whether in electronic or hard copy format. Thank you. ---------------------------------------------------------------------- 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
