Browse Prior Art Database

Decreasing Address Space in a Mass Storage Apparatus

IP.com Disclosure Number: IPCOM000084376D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Honomichl, LL: AUTHOR [+2]

Abstract

In mass storage systems of the multilevel type, a lower level may consist of a magnetic tape storage and retrieval unit such as shown in U.S. Patent 2,941,738; while the upper level may either be a semiconductor memory, a bubble memory, or a magnetic storage disk memory (DASD). In other mass storage systems, the lower level may be large capacity disk storage units (DASD) with a semiconductive memory as the upper level. In such multi-level mass storage systems, a given address space is associable through table look-up procedures with certain physical storage portions of the lower level; for example, when a tape storage and retrieval unit is a lower level, one or more tape reels may be logically associable with a given defined address space which may be termed a virtual volume.

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Decreasing Address Space in a Mass Storage Apparatus

In mass storage systems of the multilevel type, a lower level may consist of a magnetic tape storage and retrieval unit such as shown in U.S. Patent 2,941,738; while the upper level may either be a semiconductor memory, a bubble memory, or a magnetic storage disk memory (DASD). In other mass storage systems, the lower level may be large capacity disk storage units (DASD) with a semiconductive memory as the upper level. In such multi-level mass storage systems, a given address space is associable through table look- up procedures with certain physical storage portions of the lower level; for example, when a tape storage and retrieval unit is a lower level, one or more tape reels may be logically associable with a given defined address space which may be termed a virtual volume.

Similarly, certain cylinders of a lower level DASD storage unit may be similarly associable with such a virtual volume address space.

When error conditions are encountered in such a mass storage system, it is desirable to analyze a failing unit by removing it physically from control of the mass storage system. In order to do this, the association of the address space with such physical record space must be removed or eradicated.

The above objective can be achieved by either physically removing the offending record storage unit or by logically partitioning it away from the mass storage system, such that it is no longer associable with a given address space. In the event a tape reel has caused an error condition, a second or third tape reel also logically associable with the address space may be acceptable from a recording viewpoint. Accordingly, it is desired when removing the address space from the tables associating such address space with the record unit, to release nonoffending record units for reassignment to other address spaces. Accordingly, if the record unit failing is associ...