Kees, Am I missing something? You stated that you didn't agree with me and then proceeded to agree with my premise. Stated another way: "Only migrate when you need more free space in your volume pools. Otherwise, leave it there".
This is obviously a generalization on my part and leaves a lot to the imagination of the reader. Things like cost of CPU, DASD for migrate/recalls, etc. were intentionally left out of my response as I was addressing the point of migration based on size, which, in my opinion, is putting the cart before the horse. I fear we may be talking semantics here and are actually in agreement. Bob -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Vernooy, C.P. - SPLXM Sent: Monday, July 28, 2008 10:06 AM To: IBM-MAIN@BAMA.UA.EDU Subject: Re: HSM Recalls I don't agree. First, "You don't" is not an answer to the question "how do I". "in my opinion you shouldn't" is and I think that's what you intend to say and I have a different opinion. Your reasoning is correct, until the point where you don't take the cost of migration and recalls into consideration when doing the "balancing act". I have determined that it saves me a lot of cpu not to migrate/recall "small" datasets and it only costs me a fraction more on my storagegroups. This is something missing in storage management. Fase 1 "should I start migrating" is realized, but fase 2 "how do I migrate efficiently" is not, that is what I bring into the system with leaving small datasets outside migration and what Michael also already regarded useful, but was not sure how to realize it. Kees. "Richards, Robert B." <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>... > The question posed by Michael was how does someone select datasets for > migration based on size. The answer, "You don't". Let me explain. > > The purpose of space management is to make sure that you have enough > available space in your storage pools to handle new allocations and > extending of existing allocations. Movement of datasets should only > happen to meet that end. The only reason "size matters" <grin> is > because the larger the allocation of the migration-eligible dataset is, > the easier the goal is met to provide available free space in the > storage pool. > > To that end, I agree with Ted. Migrating datasets based solely on some > minimum size is ludicrous, especially if it is a very small value. > > We all know that placing datasets on L0, L1 and L2 is a balancing act > based on constraints that vary shop-to-shop and definitely change over > time. > > Bob > > --------------------------------------------------------- > Robert B. Richards (Bob) > US Office of Personnel Management > 1900 E Street NW Room: BH04L > Washington, D.C. 20415 > Phone: (202) 606-1195 > Email: [EMAIL PROTECTED] > --------------------------------------------------------- > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of Vernooy, C.P. - SPLXM > Sent: Monday, July 28, 2008 9:12 AM > To: IBM-MAIN@BAMA.UA.EDU > Subject: Re: HSM Recalls > > The down side of this method is that you only have one chance to > determine the size, at dataset creation. Whatever happens to (the size > of) the dataset afterwards is out of ACS routines control. > We have CA-DISK and there I can (and do) explicitely exclude datasets > from archiving/migration based on the size at that moment. > > Kees. > > "O'Brien, David W. [C] , NIH/CIT" <[EMAIL PROTECTED]> wrote in > message > news:<[EMAIL PROTECTED]>... > > Not HSM, selection is done by assigning SMS Management class based on > size in the SMS ACS routine. > > > > ________________________________ > > > > From: Michael Wickman [mailto:[EMAIL PROTECTED] > > Sent: Mon 7/28/2008 8:55 AM > > To: IBM-MAIN@BAMA.UA.EDU > > Subject: Re: HSM Recalls > > > > > > > > Just curious how you select for migration base on size. Do you set > > special management class based on primary space at allocation time? > Or > > are there HSM commands that help with this selection process? > > > > > > *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* > > Mike Wickman > > Technical Services > > email mwickman at waddell dot com > > *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* > > > > -----Original Message----- > > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > > Behalf Of Ted MacNEIL > > Sent: Thursday, July 24, 2008 4:56 PM > > To: IBM-MAIN@BAMA.UA.EDU > > Subject: Re: [IBM-MAIN] HSM Recalls > > > > >We do not migrate anything smaller than 5mb since the overhead of > > migrating them and having them recalled later was greater than the > cost > > of just leaving them on disk! > > > > I mentioned this on IBM-Main many years ago. > > I was told I was full of s**t. > > Back then, it was any dataset a cylinder (.8 MB) or smaller. > > Now, I think even 5MB is probably small. > > > > Analysis is required, but the concept is sound. > > > > ---------------------------------------------------------------------- > 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 > ********************************************************************** For information, services and offers, please visit our web site: http://www.klm.com. 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