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Chapter 5: Windows backup and restore

This book excerpt is from Chapter 5 of Inside Windows Storage by Dilip Naik and examines backup and restore technologies in-depth.

Inside Windows Storage

Chapter 5: Backup and Restore Technologies

This book excerpt is from Chapter 5 of Inside Windows Storage by Dilip Naik which discusses some of the technical challenges associated with backing up and restoring data. This chapter also explores various ways to classify backup and restore techniques, using volume shadow copy service to take a snapshot in Windows Server 2003, and how the Network Data Management Protocol (NDMP) fits into Microsoft's vision of managing your storage.

Backup is the process whereby a coherent copy of data is made. Backup has become more important as the amount of data has exploded, not just in importance, but in volume as well. One study estimates that more data will be created in the next few years than has been created since the dawn of history! It is interesting to compare the growth in data storage with the more widely known and appreciated growth in electronic chip density. Recall that Moore's law implies that the amount of electronics on a given chip area doubles every 18 months. A lot of industry analysts believe that the growth in digital storage is actually handily beating Moore's law in the sense that the amount of data doubles in much less than 18 months.

Historically, tape has been used as a medium for backing up data. Initially tape was a much cheaper medium than disk. Subsequently it was argued that optical media would become the media of choice, but for various reasons this vision never came to fruition. Although the medium of choice (for backup) remains predominantly tape, regular disk drives are increasingly becoming the medium of choice for an initial backup and system mirror. This trend is due mainly to the falling prices of disk storage, which reduces the cost advantage of tape over disk storage. Another reason for the increasing use of disk-based backup is the higher speed, which ensures minimal downtime for server-based applications.

Note that both disk and tape as media for backup have their advantages and disadvantages, and both will continue to be used. Tape-based backup/restore offers a very high-density medium that can easily be transported for off-site archive or disaster recovery purposes. When an initial copy of data is made to disk, very often a secondary backup operation to traditional tape media is made from that disk-based copy.

This chapter explains the technical challenges that need to be solved in order to back up and restore data in a timely way. The chapter also explains the various ways in which backup/restore techniques can be classified. Also included are discussions of new developments in WindowsServer 2003 for accomplishing snapshots (volume shadow copy service) and of the Network Data Management Protocol (NDMP) and how it fits into the Microsoft vision of storage management.

This chapter includes sections on the following topics:

  • Reasons for Backup and Restore
  • Backup Problems
    • The Backup Window
    • Explosion of APIs
    • Open Files Problem
  • Backup Classifications
    • Backup Classifications Based on Architecture
      • Image- or block-level backup
      • File-level backup
      • Application-level backup
    • Backup Classifications Based on Functionality
      • Full Backup
      • Differential Backup
      • Incremental Backup
    • Backup Classifications Based on Network Infrastructure
      • Direct-Attached Backup
      • Network-Attached Backup
      • LAN-Free Backup
      • Server-Free Backup
      • The Windows Server Family and Server-Free Backup
  • Windows 2000 Backup Utility
  • Techniques to Create a Volume Snapshot
  • Windows XP and Windows Server 2003 Volume Shadow Copy Service
    • Writers
    • Requestors
    • Volume Shadow Copy Service
    • Providers
    • Windows-Powered NAS Devices and Snapshots
  • Network Data Management Protocol
  • NDMP Architecture
    • Data Mover Agent
    • NDMP Services
    • NDMP Sessions
  • Practical Implications
  • Summary

This chapter is posted in full as a pdf file. To continue reading, click here.

Inside Windows Storage, ISBN 0-321-12698-x, copyright 2004. All rights reserved. This chapter, titled "Backup and Restore Technologies," is posted with permission from Pearson Education, Inc. Publishing as Pearson Addison-Wesley.

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