On Wed, 17 May 2006 10:25:01 -0000, Dusha, Cecelia Ms. WHS/ITMD <[EMAIL PROTECTED]> wrote:
>The 3390 mod 9 are not large enough for the customer's application. > >What is the largest volume z/VM 5.1 can handle? If only the data utiliz ed >the one huge volume, what would be the repercussions? > >Please advice. > >Cecelia Dusha >======================== ========================= ======================== Cecelia, The current limit on 3390 size on your DS6800 is 65520 cylinders. In you r case, running NOMAD, you'll hit the limitation caused by CMS needing to keep all it's file status and control information below 16M in virtual storage. So 32767 cylinders is about the practical limit for a single CM S MDISK. There is some information about this in the z/VM 5.2 CP Planning and Administration manual under the MDISK statement. Not sure if the sam e note is in your 5.1 version of the manual, but it still applies. Repercussions of one large volume in your environment would mostly be los s of I/O concurrency if it is a shared database. Your backup & recover y is one big HIDRO stream anyway, so the number of volumes is not a factor. Other considerations would revolve around loss of flexibility from having volumes of different sizes. (eg. you're stuck needing a volume that size when you FLASHCOPY it, move it to a different LCU, go to DR, or make a copy of it for testing.) I don't know NOMAD's capability for spreading it's data across several MDISKS, but it would be very wise to do it if NOMAD can. Eventually the point will be reached where even the largest MDISK will not be enough and then the application is SOL if it can't use multiple MDISKS. So the earlier they use multiple MDISKs the less pain they'll encounter later. Brian Nielsen
