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Method for selective replay of journal entries to improve performance for object recovery in a journalled environment.

IP.com Disclosure Number: IPCOM000022688D
Original Publication Date: 2004-Mar-25
Included in the Prior Art Database: 2004-Mar-25
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Abstract

Disclosed is a method for selective replay of journal entries to improve performance for object recovery in a journalled environment.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 79% of the total text.

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Method for selective replay of journal entries to improve performance for object recovery in a journalled environment .

In a journalled environment, the recovery of a damaged or corrupted object often requires the replay of a set of journal entries to return the object to a valid state. This is done by sequentially replaying the all entries in that set. Each replay operation can be time consuming, and some entries may have no impact on the final state of the object because subsequent entries will overlay or replace the previous changes. This performance problem can be improved by intelligently selecting the entries required to recover the object rather than sequentially replaying all the entries. Only replay entry types for operations that will affect the final state of the object.

     Example 1: if a journalled stream file has three change owner entries in the set of entries to be replayed, then only replay the last (third) change owner entry. The first and second change owner entries do not affect the final state of the object.

     Example 2: if a journalled stream file has many write entries followed by a truncate to 0 entry, then only replay the truncate entry. The previous write entries do not affect the final state of the object.

     The concept of only replaying operations that will affect the final state of the object could possibly be adopted in other applications that do replay type operations, such as applications that do replication.

     Implementation can be done ma...