A DB2 Performance Tuning Roadmap --LOG INTRODUCTION

A DB2 Performance Tuning Roadmap --LOG INTRODUCTION

本文的内容是在整理报表时，对DB2 STAT LOG AVITIVITY部分的一个补充，主要介绍了DB2 LOG作用，overhead，涉及的部件以及部件之间的工作机制如何利用DB2 log，现有的IBM 提供的 DB2 Log utilities。最后对DB2 log的逻辑给出一个感性的认识。

• 1 LOG OVERVIEW
  • DB2 LOG FUNDAMENTALS
    • LOG AIM:
    • WHY NEED LOGGING
    • IN PERFECT WORLD
    • OVERVIEW OF LOG WORK MECHANISM
• 2 UNDERSTANDING OF LOG
  • LOG IMPLEMENTATION
    • 1 LOG RBA
    • 2 WHEN DATA SHARING INVOLED-LRSN
    • 3 LOG PAGE DATA SETS
      • FACTORS OF ACTIVE LOG DATA SETS:
      • BSDS – Boot Strap Data Set
      • SYSLGRNX-DLD
      • FACTORS OF ARCHIVE LOG DATASETS
  • LOG STRUCTURE
    • WHAT IS BEING LOGGED?
      • INFORMATION OF UR
      • PAGE SET INFORMATION
      • RECOVERY INFOMATION FOR
      • SYSTEM CHECKPOINTS
      • UNDO/REDO LOG EXMPLAE
      • COMPENSATION OF LOG EXMPLE
      • RECOVERY INFORMATION EXAMPLE
      • SYSTEM CHECKPOINTS DETAIL
    • WHEN IS LOGGING
  • LOG USAGE
    • Start DB2
    • Recovery of objects
    • REPLICATION
    • SOX Compliance
    • HEALTH CHECKS
  • LOG UTILITES,WORKING WITH THE LOG
    • DSN1LOGP
    • DSNJU004、DSNJU003
      • DSNJU004
      • DSNJU003 (a.k.a Change Log Inventory)
    • DSNJLOGF
    • RECOVER BSDS
      • #RECOVER BSDS
• LOG RELATED DATASET
  • LOG PAGE FORMAT

1 LOG OVERVIEW

DB2 LOG FUNDAMENTALS

LOG AIM:

The DB2 log has two main functions: to reapply or back out units of recovery, and to rebuild DB2 back to a consistent state in the event of a failure

WHY NEED LOGGING

1. overhead
2. it costs in ters of performance,dasd,dministration,cleanup
3. it's assurance-just in case of an accidentIN PERFECT WORLD
   1. no need to rollback
   2. no need to recover
   3. no program errors
   4. no hardware errors
   5. no power failtures
   6. no hurricances,terror attacks,fraud....

Let’s get the MOST out of the LOG since it’s here

OVERVIEW OF LOG WORK MECHANISM

USAGE OF EACH COMPONENTS

1. Active logs
   Where DB2 puts the current log information
2. Log Buffers
   Where log information is held BEFORE externalisation to DASD