Browse Prior Art Database

Moving Data Sets From Backup Volumes to Active Volumes

IP.com Disclosure Number: IPCOM000048071D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Bittihoffer, JR: AUTHOR

Abstract

In peripheral storage, active volumes, such as direct access storage devices (DASDs) of high performance act as a front store. Backup volumes, i.e., lower performance volumes, such as magnetic tape and lower performance DASD, receive those data sets from the active volumes as backup. Occasionally, the data sets stored in the backup volumes have to be retrieved. To efficiently retrieve the backup volumes, sequence numbers are assigned to the data sets as they are lodged in the backup volumes. Recovery then is based upon of a magnetic tape will recover all data sets on that volume desired to be recovered at the particular time.

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Moving Data Sets From Backup Volumes to Active Volumes

In peripheral storage, active volumes, such as direct access storage devices (DASDs) of high performance act as a front store. Backup volumes, i.e., lower performance volumes, such as magnetic tape and lower performance DASD, receive those data sets from the active volumes as backup. Occasionally, the data sets stored in the backup volumes have to be retrieved. To efficiently retrieve the backup volumes, sequence numbers are assigned to the data sets as they are lodged in the backup volumes. Recovery then is based upon of a magnetic tape will recover all data sets on that volume desired to be recovered at the particular time.

Backup volumes on DASD are assigned an arbitrary sequence number, such as -1, to indicate that the sorting for tape motion control is unnecessary. Sorting the -1 data sets to be recovered can be by track and cylinder for reducing head motion in the same way that recovery from a tape member is sorted for minimizing motion.

The peripheral storage includes a control, such as a plurality of control units, as well as programming in the user hosts which operate the peripheral systems. A front store includes a plurality of DASDs of the high performance type. When data sets are moved from the control to a given volume, such as a DASD or tape, a sequence number SEQ is assigned to each data set. A table is constructed (not shown) in the host and stored on some DASD which relates the sequence number to the data set...