Browse Prior Art Database

Non-Retentive Data Identifier (NRDID)

IP.com Disclosure Number: IPCOM000037502D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Beardsley, BC: AUTHOR [+4]

Abstract

A cached DASD (Direct Access Storage Device) subsystem may, to improve performance on write operations, allow write operations to cache without concurrently updating a non-volatile storage (DASD or Non-volatile Storage). A cache failure causes the status of that data to be unknown and the user must be notified that his data may be lost. The notification should only be given to users of Non-Retentive Data. The NRDID provides the means of providing this notification.

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Non-Retentive Data Identifier (NRDID)

A cached DASD (Direct Access Storage Device) subsystem may, to improve performance on write operations, allow write operations to cache without concurrently updating a non-volatile storage (DASD or Non-volatile Storage). A cache failure causes the status of that data to be unknown and the user must be notified that his data may be lost. The notification should only be given to users of Non-Retentive Data. The NRDID provides the means of providing this notification.

A user can specify Non-Retentive Data when he wants to improve write performance and is willing to assume the exposure of losing the data in the event of cache failure. Non-Retentive Data should be used only when the data is easily recoverable.

The NRDID provides a means for the users of Non-Retentive Data to be notified when they have been exposed to a loss of data and to limit that notification (and the resulting job termination) to only users of Non-Retentive Data.

The NRDID is used to assure that a Non-Retentive Data user does not access down level data as the result of loss of cached data.

The NRDID is generated by the SDs (Storage Directors) in the subsystem and a single ID exists for the subsystem as long as the subsystem is operational.

The NRDID is an unsigned 2 byte counter with all values except zero valid.

The current NRDID is incremented by +1 whenever caching is terminated (or reinitialized) and at IML (Initial Microprogram Load) when the possibility...