That is why I said, "Granted, for all other devices, it is best to allocate cylinder 0 as perm. There you have a guarantee that the volume label will get wiped out if that cylinder is included in a user minidisk."
If you are trying to wipe out the label on an active page or spool volume that is so allocated from 0 to end, you must work at it and it must be intentional. Also, do you not create minidisks for the areas allocated to PAGE or SPOL? That would include cylinder 0, so you would still have that protection. Regards, Richard Schuh > -----Original Message----- > From: The IBM z/VM Operating System > [mailto:[EMAIL PROTECTED] On Behalf Of Thomas Kern > Sent: Tuesday, June 24, 2008 2:35 PM > To: IBMVM@LISTSERV.UARK.EDU > Subject: Allocating Cyl Zero as Perm (Was: Performance > toolkit under zVM 5.3) > > I have never seen a problem with CP stepping on the Label. I > have stepped on it myself and seen other inexperienced people > step on it. > That is why I always allocate cylinder zero of a VM volume as > perm and allocate a one cylinder minidisk owned by VMDASD > there. That is the "best practices" guideline that I follow. > > /Tom Kern > > Schuh, Richard wrote: > > Assuming that you have free slots in the CP_Owned list. > > > > It is documented that CP understands and will preserve that part of > > cylinder 0 if a volume is allocated from 0-nnn as a PAGE or > SPOL pack > > and that doing so is OK. Do you know of an actual problem > (in the last > > 15 years) caused by allocating 0 to END as PAGE or SPOL? Anecdotal > > evidence does not count; neither do examples from before > the time that > > doing so became supported. There is probably no good reason > to leave > > tracks 1-15 unused on a paging or spooling volume. The only > thing that > > needs protecting on these volumes is cylinder 0 track 0, > and a clever > > CP might even be able to use part of it for these functions. > > > > This may be a case of "best practices" being based on fairy tales, > > myths, or outdated experience. Granted, for all other > devices, it is > > best to allocate cylinder 0 as perm. There you have a > guarantee that > > the volume label will get wiped out if that cylinder is > included in a > > user minidisk. > > > > > > > > Regards, > > Richard Schuh > > >
