Browse Prior Art Database

DASD Characteristics Stored in Volume Label

IP.com Disclosure Number: IPCOM000046770D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Phillips, GH: AUTHOR

Abstract

A plurality of direct-access storage devices (DASDs) may be accessed by a central processing unit (CPU), and any one of these DASDs may be transferred from one CPU to another. In order for a CPU to access one of these DASDs, it is necessary for the CPU to ascertain the characteristics of the device. If different DASDs having dissimilar characteristics are being used, it has typically been required that the CPU go through operator system generation each time a device is accessed. This is a waste of CPU time. This problem is overcome by determining the characteristics required to access the device and storing those characteristics in the extension portion of the standard volume label of the device. Preferably, the characteristics stored are the following: 1.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

DASD Characteristics Stored in Volume Label

A plurality of direct-access storage devices (DASDs) may be accessed by a central processing unit (CPU), and any one of these DASDs may be transferred from one CPU to another. In order for a CPU to access one of these DASDs, it is necessary for the CPU to ascertain the characteristics of the device. If different DASDs having dissimilar characteristics are being used, it has typically been required that the CPU go through operator system generation each time a device is accessed. This is a waste of CPU time. This problem is overcome by determining the characteristics required to access the device and storing those characteristics in the extension portion of the standard volume label of the device. Preferably, the characteristics stored are the following: 1. Device type (for accessing and error correction

purposes).

2. Maximum allocation groups in this volume.

3. Number of cylinders in this volume.

4. Number of heads per cylinder.

5. Number of paging blocks per track.

6. Sector addresses associated with the paging blocks.

7. Number of paging blocks per volume.

8. ID of last sector on this volume.

9. System usage of this volume. The maximum allocation groups and number of cylinders indicates the logical space available, not necessarily the amount of physical space. This permits the use of virtual machine minidisks.

1