HP StorageWorks 4000s NAS 4000s and 9000s Administration Guide - Page 53

Storage Management Overview Storage Elements Overview The NAS server offers optimized performance for a growing environment. Storage capacity can increase as a business grows without downtime or compromised performance. Storage limitations are based on the type of SAN the NAS server is connected to. See the individual SAN documentation for limitations of Windows Storage Server 2003. Preliminary physical storage management tasks involve managing: ■ Physical Hard Drives ■ Arrays ■ Logical Drives (LUNs) Drive array concepts and data protection methods, including fault tolerance options are discussed in this section. This information will help guide decisions on how to best configure the arrays. Physical Hard Drives For personal or small business use, the capacity and performance of a single hard drive is adequate. However, larger businesses demand higher storage capacities, higher data transfer rates, and greater security from data loss if drives fail. Merely adding extra drives to the system increases the total storage capacity, but has little effect on the system efficiency, because data can only be transferred to one hard drive at a time. Figure 24 illustrates the read/write process with separate physical hard drives. R/W P1 P2 P3 Arrays Figure 24: Separate physical drive (P1, P2, P3) read/write (R/W) operations With an array controller installed in the system, the capacity of several physical drives can be logically combined into one or more logical units called arrays. When this is done, the read/write heads of all the constituent physical drives are active simultaneously, dramatically reducing the overall time required for data transfer. NAS 4000s and 9000s Administration Guide 53