Chapter 2 HPSS Planning
HPSS Installation Guide September 2002 93
Release 4.5, Revision 2
Figure 2-2 Relationship of Class of Service, Storage Hierarchy, and Storage Class
2.9.1 Storage Class
Eachvirtual volume and its associated physical volumes belong to some storage class in HPSS. The
SSMprovides the capability to define storage classes and to add and delete virtual volumes to and
fromthe defined storage classes. A storage class is identified by a storage class ID and its associated
attributes. For detailed descriptions of each attribute associated with a storage class, see Section
6.7.1: Configurethe Storage Classes (page 305). Once a storage class has been defined, great care must
betaken if the definition is to be changed or deleted. This especially applies to media and VV block
size fields.
The sections that follow give guidelines and explanations for creating and managing storage
classes.
2.9.1.1 Media Block Size Selection
Guideline: Select a block size that is smaller than the maximum physical block size that a device
driver can handle.