The answer is - it depends. When an SMS Pool, SMS determines where to place datasets. So you have to make the VTOC large enough to hold any number of datasets.
And that number is dependent on the size of the datasets. You need a larger vtoc if you have small files, and a smaller one will work if you only have large files. You have to also consider datasets that can span volumes in an SMS pool that may have a small secondary allocation. So if you can determine that the SMS pool will only get large allocations, you could be okay. But I like to have large vtocs in-case there are unexpected file sizes. That way you do not run into a situation where you have to expand the VTOC or VVDS unexpectedly. I also allocate in Cylinders and not Tracks. Lizette > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf > Of esmie moo > Sent: Monday, January 21, 2013 7:00 AM > To: [email protected] > Subject: VTOC QUESTION > > Good Morning Gentle Readers, > > What are the advantages of having a large VTOC defined when initializing a volume > besides having a large amount of Free DSCBS? Would a smaller VTOC cause > response time problems? > > For example I am adding 3390-9 volumes (10,017 cyls per volume) to a STORAGE > GROUP which will only alloc certain dsns which are equal or larger than 1,500 cylinders. > > From my rough estimation not more than 650 dsns would fit on that volume. Could a > vtoc of 29 trks suffice? > > Thanks for your welcoming comments in advance. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
