Browse Prior Art Database

Usage of Data Space

IP.com Disclosure Number: IPCOM000104146D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Schmidt, H: AUTHOR

Abstract

Virtual disks may be defined in data spaces. For each virtual disk defined, a separate data space is allocated. Since the virtual disk may be used by a program running in any partition, the data space needed for the disk has to be created with the attribute SCOPE=COMMON. Therefore, whenever a partition is allocated, one entry in the access list (PASN-AL) is reserved for each defined virtual disk.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 61% of the total text.

Usage of Data Space

      Virtual disks may be defined in data spaces.  For each virtual
disk defined, a separate data space is allocated.  Since the virtual
disk may be used by a program running in any partition, the data
space needed for the disk has to be created with the attribute
SCOPE=COMMON.  Therefore, whenever a partition is allocated, one
entry in the access list (PASN-AL) is reserved for each defined
virtual disk.

      Before a virtual disk may be used, its size and layout must be
defined and the virtual disk must be initialized.  In VSE/ESA*, for
example, this is done by the VDISK command which has the format

VDISK (UNIT=cuu,BLKS=nnnnnnn[VOLID=volser][VTOC= vvv]).

      The operand UNIT=cuu indicates the channel and unit number
assigned to the virtual disk.  The operand BLKS=nnnnnnn specifies the
size of the virtual disk as a number of 512-byte blocks.  It may
range from 1 to 9,999,999.  A 0 may also be specified in order to
indicate that the virtual disk is no longer to be used and the data
space deallocated.  The VOLID operand specifies the volume serial
number of the virtual disk.  The VTOC operand specifies the number of
512-byte blocks al located for the VTOC.

      Pointers and tables have to be established to indicate to the
supervisor that a virtual disk has been created.  This is done in
VSE/ESA by a macro DEFSIM which establishes pointers that are used by
the supervisor whenever an I/O request is issued for a device
specif...