ABCs of z/OS System Programming Volume 3 - IBM Redbooks

3.2 Large volumes before z/OS V1R10
A "large volume" is larger than a 3390-9
The largest possible volume has 65520 (3390) cylinders
That would be a "3390-54" if it had its own device type
Almost 54 GB
3390-27
32760 Cyls
Figure 3-2 Large volume support 3390-54
3390-54
65520 Cyls
Large volume support
The IBM TotalStorage Enterprise Storage Server (ESS) initially supported custom volumes of
up to 10017 cylinders, the size of the largest standard volume, the 3390 model 9. This was
the limit set by the operating system software. The IBM TotalStorage ESS large volume
support enhancement, announced in November 2001, has now increased the upper limit to
65520 cylinders, approximately 54 GB. The enhancement is provided as a combination of
IBM TotalStorage ESS licensed internal code (LIC) changes and system software changes,
available for z/OS and z/VM®.
Today, for example, the IBM Enterprise Storage Server emulates the IBM 3390. On an
emulated disk or on a VM minidisk, the number of cylinders per volume is a configuration
option. It might be less than or greater than the stated number. If so, the number of bytes per
device will differ accordingly. The IBM ESS Model 1750 supports up to 32760 cylinders and
the IBM ESS Model 2107 supports up to 65520 cylinders.
Large volume support is available on z/OS operating systems, the ICKDSF, and DFSORT
utilities.
Large volume support must be installed on all systems in a sysplex prior to sharing data sets
on large volumes. Shared system and application data sets cannot be placed on large
volumes until all system images in a sysplex have large volume support installed.
Chapter 3. Extended access volumes 55