There is a HSM migration exit(ARCMDEXT) that gets control when a dataset is going to be moved from L0 to L1, L1 to L2. The great thing about the exit is there is one piece of information that is not known where the management class is assigned: The actual size of the data set. That is passed to the exit so you could keep 100 5 cyl datasets around on L1 and send one 500 cyl dataset directly to L2 for the same amount of online storage.
Duane Reaugh DTS Software (makers of Easy/Exit that supports this exit if you don't want to write and maintain a exit) sorry -----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: [email protected] 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: [email protected] > 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: [email protected] > > 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: [email protected] > > 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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