2 Implementing the IBM Storwize V7000 with IBM Spectrum Virtualize V8.2.1
1.1  Storage virtualization terminology
Storage virtualization is a term that is used extensively throughout the storage industry. It can 
be applied to various technologies and underlying capabilities. In reality, most storage devices 
technically can claim to be virtualized in one form or another. Therefore, this chapter starts by 
defining the concept of storage virtualization as it is used in this book.
IBM describes storage virtualization in the following way:
/SM590000Storage virtualization is a technology that makes one set of resources resemble another 
set of resources, preferably with more desirable characteristics.
/SM590000It is a logical representation of resources that is not constrained by physical limitations and 
hides part of the complexity. It also adds or integrates new function with services and can 
be nested or applied to multiple layers of a system.
Storage virtualization is also defined in the Storage Networking Industry Association’s (SNIA) 
shared storage model version 2, as shown in Figure 1-1. 
Figure 1-1   SNIA shared storage model, version 21
The model consists of the following layers:
/SM590000Application: The user of the storage domain.
/SM590000Storage domain:
– File/record/namespace virtualization and File/record subsystem
– Block Virtualization
– Block subsystem
Applications typically read and write data as vectors of bytes or records. However, storage 
presents data as vectors of blocks of a constant size (512 or in the newer devices, 4096 bytes 
per block). 
1  Source: Storage Networking Industry Association.