IBM DS6000 Series manual Introduction to Copy Services, Copy Services functions

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.

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.

See Figure 6-1 on page 91 for an illustration of FlashCopy concepts.

90DS6000 Series: Concepts and Architecture