Browse Prior Art Database

Multilevel Store Directory Integrity

IP.com Disclosure Number: IPCOM000088809D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Blickenstaff, RL: AUTHOR [+3]

Abstract

A multilevel store is addressed from host to virtual addressing techniques. As a result, directories to the data stored in the device groups A, B and C, such as DASD spindles, are necessary for accessing the data. A mass storage control (MSC), also connected to the host, controls the staging adaptors and insures that the directories are appropriately updated, not only in the staging adaptors but also in the MSC and in directories stored on the spindles A, B, C. Such DASD spindles constitute an upper level store while a lower level store is a data base storage, preferably of a tape-library type. In the virtual address space the addressing is a single address field.

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Multilevel Store Directory Integrity

A multilevel store is addressed from host to virtual addressing techniques. As a result, directories to the data stored in the device groups A, B and C, such as DASD spindles, are necessary for accessing the data. A mass storage control (MSC), also connected to the host, controls the staging adaptors and insures that the directories are appropriately updated, not only in the staging adaptors but also in the MSC and in directories stored on the spindles A, B, C. Such DASD spindles constitute an upper level store while a lower level store is a data base storage, preferably of a tape-library type. In the virtual address space the addressing is a single address field.

For reliability purposes, the directories essential to accessing data are kept in duplicate in DASD store to insure that a good copy is always available. It is preferred that duplicate copies be kept in different DASD groups A or B, B or C, and so forth. Any time a permanent error is detected in the spindles storing the directories, operations involving the updating of the tables are momentarily suspended. Access to the data signals stored in groups A, B and C via the directories, without altering the directories, is maintained. During this suspension of directory update, a copy of a remaining good (error free) directory is made on another DASD spindle. As soon as the directory has been fully copied, normal operations resume.

The error condition reported by the spind...