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90 DS6000 Series: Concepts and Architecture
6.1 Introduction to Copy Services
Copy Services is a collection of functions that provides disaster recovery, data migration, and
data duplication functions. With the copy services functions, for example, you can create
backup data with little or no disruption to your application, and you can back up your
application data to a remote site for disaster recovery.
Copy Services run on the DS6000 server enclosure and support open systems and zSeries
environments. These functions are supported also on the previous generation of storage
systems called the IBM TotalStorage Enterprise Storage Server (ESS).
Many design characteristics of the DS6000 and data copying and mirroring capabilities of the
Copy Services features contribute to the protection of your data, 24 hours a day and seven
days a week. The licensed features included in Copy Services are the following:
FlashCopy, which is a Point-in-Time Copy function
Remote Mirror and Copy functions, previously known as Peer-to-Peer Remote Copy or
PPRC, which include:
– IBM TotalStorage Metro Mirror, previously known as Synchronous PPRC
– IBM TotalStorage Global Copy, previously known as PPRC Extended Distance
– IBM TotalStorage Global Mirror, previously known as Asynchronous PPRC
We explain these functions in detail in the next section.
You can manage the Copy Services functions through a command-line interface (DS CLI)
and a new Web-based interface (DS Storage Manager). You also can manage the Copy
Services functions through the open application programming interface (DS Open API).
When you manage Copy Services through these interfaces, these interfaces invoke Copy
Services functions via the Ethernet network. In zSeries environments, you can invoke the
Copy Service functions by TSO commands, ICKDSF, the DFSMSdss utility, and so on.
We explain these interfaces in 6.3, “Interfaces for Copy Services” on page 108.
6.2 Copy Services functions
We describe each function and the architecture of the Copy Services in this section.
6.2.1 Point-in-Time Copy (FlashCopy)
The Point-in-Time Copy feature, which includes FlashCopy, enables you to create full volume
copies of data. When you set up a FlashCopy operation, a relationship is established between
the source and target volumes, and a bitmap of the source volume is created. Once this
relationship and bitmap are created, the target volume can be accessed as though all the
data had been physically copied. While a relationship between the source and target volume
exists, optionally, a background process copies the tracks from the source to the target
volume.
See Figure 6-1 on page 91 for an illustration of FlashCopy concepts.
Note: In this section, track means a piece of data in the DS6000; the DS6000 uses the
logical tracks to manage the Copy Services functions.