770 Implementing the IBM Storwize V7000 with IBM Spectrum Virtualize V8.2.1
Commonly encountered terms
This book uses the common IBM Spectrum Virtualize and IBM Storwize V7000 terminology 
listed in this section.
Array
An ordered collection, or group, of physical devices (disk drive modules) that are used to 
define logical volumes or devices. An array is a group of drives designated to be managed 
with a Redundant Array of Independent Disks (RAID).
Asymmetric virtualization
Asymmetric virtualization is a virtualization technique in which the virtualization engine is 
outside the data path and performs a metadata-style service. The metadata server contains 
all the mapping and locking tables, and the storage devices contain only data. See also 
“Symmetric virtualization” on page 786.
Asynchronous replication
Asynchronous replication is a type of replication in which control is given back to the 
application as soon as the write operation is made to the source volume. Later, the write 
operation is made to the target volume. See also “Synchronous replication” on page 786.
Automatic data placement mode
Automatic data placement mode is an Easy Tier operating mode in which the host activity on 
all the volume extents in a pool are “measured,” a migration plan is created, and then 
automatic extent migration is performed.
Auxiliary volume
The auxiliary volume that contains a mirror of the data on the master volume. See also 
“Master volume” on page 780, and “Relationship” on page 784.
Available (usable) capacity
See “Capacity” on page 771.
Back end
See “Front end and back end” on page 777.
Caching I/O Group
The caching I/O Group is the I/O Group in the system that performs the cache function for a 
volume.
Call home
Call home is a communication link that is established between a product and a service 
provider. The product can use this link to call IBM or another service provider when the 
product requires service. With access to the machine, service personnel can perform service 
tasks, such as viewing error and problem logs or initiating trace and dump retrievals.
Canister
A canister is a single processing unit within a storage system.