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290 DS6000 Series: Concepts and Architecture
15.1 Introduction
The term data migration has a very diverse scope. We use it here solely to describe the
process of moving data from one type of storage to another, or to be exact, from one type of
storage to a DS6000. In many cases, this process is not only comprised of the mere copying
of the data, but also includes some kind of consolidation.
With our focus on storage, we distinguish three kinds of consolidation, also illustrated in
Figure 15-1:
The consolidation of distributed, direct-attached storage to shared, SAN-attached disk
storage
The consolidation of many small volumes into a few larger ones
The consolidation of several small storage systems into a few larger ones
Figure 15-1 Different ways of consolidation
Very often, the goal of a consolidation effort is a combination of more than one of these types.
There are many different methods for data migration. To decide on what is best in your case,
gather information about the following items:
The source and target storage make and type
The amount of data to be migrated
The amount of time available for the migration
The ability to connect both source and target storage at the same time
The availability of spare disk or tape capacity for temporary storage
The format of the data itself
The consolidation goals
Can the migration be disruptive, and for how long?
The distance between source and target
We describe the most common methods in the next section. Be aware that, in a
heterogeneous IT environment, you will most likely have to choose more than one method.
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Few larger volumes
Collection of small volumes
Several storage subsystems
Host
Direct attached storage
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