Browse Prior Art Database

Demounting Unidentified Virtual Volumes

IP.com Disclosure Number: IPCOM000088602D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Kuser, TT: AUTHOR [+2]

Abstract

A mass storage system (MSS) consisting of a mass storage control (MSC), a plurality of staging adaptors (INSA), a mass storage facility (MSF), and a staging storage facility (SSF) is virtually addressed from a plurality of central processing unit (CPU) hosts. Additionally, one of the CPU hosts is a primary host for providing host control over the MSC. In the rare event one of the hosts powers down, system resets or re-IPLs (initial program loads), its tables (unit control blocks (UCBs)) are lost. Such tables relate virtual volumes (VV) to virtually mounted units (VUAs) which are realized as address bases in plural independent units (IUs), of SSF. Each CPU host using a VV identifies same by a volume identification (VOLID). Such VOLIDs are maintained in volatile memory (not shown) of each host.

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Demounting Unidentified Virtual Volumes

A mass storage system (MSS) consisting of a mass storage control (MSC), a plurality of staging adaptors (INSA), a mass storage facility (MSF), and a staging storage facility (SSF) is virtually addressed from a plurality of central processing unit (CPU) hosts. Additionally, one of the CPU hosts is a primary host for providing host control over the MSC. In the rare event one of the hosts powers down, system resets or re-IPLs (initial program loads), its tables (unit control blocks (UCBs)) are lost. Such tables relate virtual volumes (VV) to virtually mounted units (VUAs) which are realized as address bases in plural independent units (IUs), of SSF. Each CPU host using a VV identifies same by a volume identification (VOLID). Such VOLIDs are maintained in volatile memory (not shown) of each host. Upon powering up from an inadvertent power down or from other causes, the VV assigned to a given VUA is unknown to that host. However, during IPL the UCB of each CPU is fetched from nonvolatile storage such as a direct-access storage device (DASD) unit, which may constitute the IUs of SSF. The VV mount states in these tables may not have the current identification of its VVs as mounted in VUAs. Any inconsistency between host UCBs and MSS mount states results in nonaddressability of VVs and useless UCBs. MSS will not demount a VV unless the requesting host has the correct VOLID. That is, the UCBs may not contain the correct mount inform...