The answer to your question is
in your xx TB dasd park when you have a handful of 3390-54's filled for 1%?
- probably none.
With virtual storage arrays for Disk, only what is used, is allocated to the
Volser. Say you have a MOD54 defined. But only 1% used. Then there is only
1% storage tied up to that Mod54. If it grows, then the storage array probably
takes from an internal Free pool and adds the extents (LUNs?) to that
definition for a MOD54 until it is maxed out at 65620 Cylinders.
So, from my perspective, it is not always good to define all one type of device
(mod54, mod27, etc...) the Internal mapping of the LUNs to those devices might
leave unused storage, or if you have something like FAST VP (EMC VMAX) then
the FASTVP may have problems properly balancing the workload inside the array.
Just my two cents worth
Lizette
> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On
> Behalf Of Vernooij, CP (ITOPT1) - KLM
> Sent: Monday, July 04, 2016 5:16 AM
> To: IBM-MAIN@LISTSERV.UA.EDU
> Subject: Re: Minimum Volume Sizes in the Wild
>
> We create as much 3390-54's as possible.
> We have some smaller volumes only because they were converted as is from
> ESS's.
> And we have some 3390-3 and 3390-1 for JES checkpoint and catalogs, but with
> the current GDPS requirement to eliminate all Reserves, I think it would not
> be a problem to combine them. On the other hand, how much space will be wasted
> in your xx TB dasd park when you have a handful of 3390-54's filled for 1%?
>
> Kees.
>
> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On
> Behalf Of John Eells
> Sent: 28 June, 2016 18:19
> To: IBM-MAIN@LISTSERV.UA.EDU
> Subject: Minimum Volume Sizes in the Wild
>
> What is the *smallest* volume size everyone sees in general use?
>
> For example, will we create any problems if we assume that "everyone"
> has or can define at least a 3390-9 size volume these days? What if we chose
> 3390-27?
>
> --
> John Eells
> IBM Poughkeepsie
> ee...@us.ibm.com
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