IBM DS6000 Series Business continuance functions, Point-in-time Copy feature, Data Set FlashCopy

1.2.5 Business continuance functions

As data and storage capacity are growing faster year by year most customers can no longer afford to stop their systems to back up terabytes of data, it just takes too long. Therefore, IBM has developed fast replication techniques that can provide a point-in-time copy of the customer’s data in a few seconds or even less. This function is called FlashCopy on the DS6000 series, as well as on the ESS models and DS8000 series.

As data becomes more and more important for an enterprise, losing data or access to data, even only for a few days, might be fatal for the enterprise. Therefore, many customers, particularly those with high end systems like the ESS and the DS8000 series, have implemented Remote Mirroring and Copy techniques previously called Peer-to-Peer Remote Copy (PPRC) and now called Metro Mirror, Global Mirror, or Global Copy. These functions are also available on the DS6800 and are fully interoperable with ESS 800 and 750 models and the DS8000 series.

Point-in-time Copy feature

The Point-in-time Copy feature consists of the FlashCopy function. The primary objective of FlashCopy is to create very quickly a point-in-time copy of a source volume on the target volume. When you initiate a FlashCopy operation, a FlashCopy relationship is created between the source volume and target volume. A FlashCopy relationship is a mapping of a FlashCopy source volume and a FlashCopy target volume. The FlashCopy relationship exists between the volume pair from the time that you initiate a FlashCopy operation until the storage unit copies all data from the source volume to the target volume, or until you delete the FlashCopy relationship if it is a persistent FlashCopy. The benefits of FlashCopy are that the point-in-time copy is immediately available for use for backups and the source volume is immediately released so that applications can be restarted, with minimal application downtime. The target volume is available for read and write processing so it can be used for testing or backup purposes. You can choose to leave the copy as a logical copy or choose to physically copy the data. If you choose to physically copy the data, a background process copies tracks from the source volume to the target volume.

FlashCopy is an additional charged feature. You have to order the Point-in-time Copy feature, which includes FlashCopy. Then you have to follow a procedure to get the key from the internet and install it on your DS6800.

To make a FlashCopy of a LUN or a z/OS CKD volume you need a target LUN or z/OS CKD volume of the same size as the source within the same DS6000 system (some operating systems also support a copy to a larger volume). z/OS customers can even do FlashCopy on a data set level basis when using DFSMSdss™. Of course the DS6000 also supports Concurrent Copy.

The DS Storage Manager’s GUI provides an easy way to set up FlashCopy or Remote Mirror and Copy functions. Not all functions are available via the GUI; instead, we recommend that you use the new DS Command-Line Interface (DS CLI), which is much more flexible.

Data Set FlashCopy

In a z/OS environment when DFSMSdss is used to copy a data set, by default FlashCopy is used to do the copy. In this environment FlashCopy can operate at a data set level.

Multiple Relationship FlashCopy

Multiple Relationship FlashCopy allows a source to have FlashCopy relationships with multiple targets simultaneously. This flexibility allows you to initiate up to 12 FlashCopy relationships on a given logical unit number (LUN), volume, or data set, without needing to first wait for or cause previous relationships to end.

10DS6000 Series: Concepts and Architecture