6.5 Backing Up Your System

6.6 Approaches to Migration

The following sections describe the different ways a server can be migrated. You should understand each type and decide which method you will use for your environment.

6.6.1 Introduction

The objective of a migration can be described in the following way. It is the movement of a server, or data/configuration which resides on that server, from one server/level of software to another server or new level of software transparent to the users of the network.

In either case, the success of the migration can be assured if

After a migration, if any of the above conditions are not met, then the migration has not been completely successful.

Failure, in any way, can adversely impact users and is a common network administrator's nightmare. However, with careful planning and preparation, such failure can be eliminated, or at the very least, minimized so as to be trivial.

6.6.2 Migration Scenarios

This book discusses three distinct approaches for migration to OS/2 Warp Server for e-business. They can be summarized as follows.

6.6.2.1 CD ROM-Based, Panel-Driven Migration

  • The panel-driven scenario involves an attended installation over the existing environment through a CD-ROM (and three boot diskettes) at the server system. The hard disk is not formatted, and the existing system configuration is migrated in the process.

  • This installation scenario is described in detail in Chapter 4. Panel-Driven Installation.

    • 6.6.2.2 CID-Based, Unattended Migration

  • This CID-based scenario involves either lightly attended or unattended installation of the product over the existing environment using CID procedures or software distribution tools, such as Netview Distribution Manager or Software Distribution. The hard disk is not formatted, and the existing system configuration is migrated in the process.

  • This installation scenario is described in detail in Chapter 5. Unattended CID Migration.

    • 6.6.2.3 Pristine Installation with Migration

  • This last migration scenario involves a pristine installation of a new piece of system hardware (which can be on either a temporary or permanent basis) using either the panel-driven or unattended CID techniques subject to administrator preference.

  • This scenario can be employed whenever migration is required to different hardware, or the hard disk must be formatted.

  • After the initial new system installation, the existing system configuration must be migrated to the new system. Since the new system is normally set up from scratch, it is common for the hard disk to be partitioned and formatted.

  • The migration scenario to new hardware is discussed in the rest of this chapter.

    • 6.6.3 Pros and Cons of Approaches

    The CD-ROM and CID-based migrations invariably impact system availability. Typically, the servers that need to be migrated will be unavailable for the duration of the migration. That is to say, the server is likely to be unavailable for the duration of the installation, restoration of any data, and any last minute configuration that is required.

    If problems are experienced during this process, down-time can increase further. Also, restoration of large data volumes takes a lot of time if some form of backup and restore is implemented.

    CID-based techniques help to minimize system down time because no user interaction is necessary. Every user question is answered through response files. CD-ROM-based migrations take a lot longer especially if detailed configuration data needs to be reentered.

    In each case, it is normal for the system administrator to perform the migration during off-peak hours, such as late at night or during the weekend.

    In a high availability environment, it is not acceptable for servers to be off-line. Therefore, it becomes desirable to adopt some form of swapping in strategy that reduces the time that the server is off-line. However, if configuration or data must also be moved, this issue becomes more complex.

    This chapter describes a tried and tested approach to migration that involves installation of a second system, the restoration of the first system's data and its configuration details to that second system, followed by a swapping in procedure.

    This approach not only addresses the high availability environment, it can also be considered when moving from one system to new hardware, whatever your reasons for doing so. We recommend this approach as a method, which, in our opinion, is the best approach to migration for a number of reasons. These are:

    6.7 The Migration