Browse Prior Art Database

Expanding Track State Possibilities of Global Metadata Tracks to Improve Access

IP.com Disclosure Number: IPCOM000124563D
Original Publication Date: 2005-Apr-28
Included in the Prior Art Database: 2005-Apr-28
Document File: 1 page(s) / 21K

Publishing Venue

IBM

Abstract

Expand valid/invalid indicators for memory copies of persistent data to include other actions that may be required before transitioning from valid to invalid or from invalid to valid.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

Expanding Track State Possibilities of Global Metadata Tracks to Improve Access

A previous disclosure entitled "On-Demand Metadata Access" details how to make Global Metadata (GMD), which is persistent data required for the control of the DS8000, accessible on demand by providing a valid/invalid indicator for the in-memory structures.

The purpose of this disclosure is to improve the functionality of the valid indicator to allow other operations on the data besides staging to be deferred. An example of other operations are initializing the data to zeros which is an operation called CST (Clear Status Tracks). Another example is recovery, which stages the data from drive and applies in-memory updates. These states prevent access to the data until the appropriate action has been taken.

Implementation is accomplished by adding track states. The track states represent CST Pending, CST failed, and Update In Progress. Access to the data that detects one of these states causes the access to block, and the required action to be initiated. In the case of CST Pending, CST is performed, which is to zero the track to an initial state. In the case of CST failed, the IO operation is always failed. No recovery is attempted. In the case of Update in Progress the recovery process is initiated.

The track state can include any other action that might be required before accessing the data.

1