Chapter 11. Advanced Copy Services 439
/SM590000Clone: Sometimes referred to as full copy. A point in time copy of a volume with 
background copy of the data from the source volume to the target. All blocks from the 
source volume are copied to the target volume. The target copy becomes a usable 
independent volume.
/SM590000Backup: Sometimes referred to as incremental. A backup FlashCopy mapping consists of 
a point in time full copy of a source volume, plus periodic increments or “deltas” of data 
that changed between two points in time.
The FlashCopy mapping has four property attributes (clean rate, copy rate, autodelete, 
incremental) and seven different states that are described later in this chapter. Users can 
perform these actions on a FlashCopy mapping:
/SM590000Create: Define a source and target, and set the properties of the mapping.
/SM590000Prepare: The system needs to be prepared before a FlashCopy copy starts. It basically 
flushes the cache and makes it “transparent” for a short time, so no data is lost.
/SM590000Start: The FlashCopy mapping is started and the copy begins immediately. The target 
volume is immediately accessible.
/SM590000Stop: The FlashCopy mapping is stopped (by the system or by the user). Depending on 
the state of the mapping, the target volume is usable or not.
/SM590000Modify: Some properties of the FlashCopy mapping can be modified after creation.
/SM590000Delete: Delete the FlashCopy mapping. This action does not delete volumes (source or 
target) from the mapping.
The source and target volumes must be the same size. The minimum granularity that IBM 
Spectrum Virtualize supports for FlashCopy is an entire volume. It is not possible to use 
FlashCopy to copy only part of a volume.
The source and target volumes must belong to the same IBM SAN Volume Controller system, 
but they do not have to be in the same I/O Group or storage pool.
Volumes that are members of a FlashCopy mapping cannot have their size increased or 
decreased while they are members of the FlashCopy mapping.
All FlashCopy operations occur on FlashCopy mappings. FlashCopy does not alter the 
volumes. However, multiple operations can occur at the same time on multiple FlashCopy 
mappings, thanks to the use of Consistency Groups.
11.1.4  Consistency Groups
To overcome the issue of dependent writes across volumes and to create a consistent image 
of the client data, a FlashCopy operation must be performed on multiple volumes as an 
atomic operation. To accomplish this method, the IBM Spectrum Virtualize supports the 
concept of Consistency Groups. 
Consistency Groups address the requirement to preserve point-in-time data consistency 
across multiple volumes for applications that include related data that spans multiple 
volumes. For these volumes, Consistency Groups maintain the integrity of the FlashCopy by 
ensuring that “dependent writes” are run in the application’s intended sequence. Also, 
Consistency Groups provide an easy way to manage several mappings.
Important: As with any T0 copy technology, you are bound by operating system and 
application requirements for interdependent data and the restriction to an entire volume.