Hub/Switch Installation Guide

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 volumeand itsassociated physicalvolumes belongtosomestorageclassinHPSS.The
SSM providesthe capability to define storageclasses and to add and deletevirtual volumes to and
fromthedefinedstorageclasses.Astorageclassis identifiedbyastorageclassIDandits associated
attributes. For detailed descriptions of each attribute associated with a storage class, see Section
6.7.1: ConfiguretheStorageClasses(page305).Oncea storageclass hasbeen defined,greatcaremust
betakenif thedefinition istobe changedor deleted.Thisespecially appliesto mediaandVV 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.