Storage Overview And Terminology; Physical Storage; Storage Arrays; Logical Storage - HP StorageWorks NAS 8000 - Version 1.6.X Manual

Network and Storage Planning

Storage Overview and Terminology

The NAS 8000 is an easy-to-manage storage solution for heterogeneous environments
including Windows, UNIX, and Linux.
The storage space on the NAS 8000 is made up of physical and logical storage:
In addition, the HA configurations include high-availability features such as redundant
hardware and failover packages.
The installation specialist works with the customer to construct an overall storage architecture,
determining the total amount of storage available and how it should be allocated to different
groups or functions. Data protection, including two RAID levels and active spare settings,
should also be considered.

Physical Storage

Storage Arrays

The NAS 8000 Dedicated Storage HA solution uses either the HP Virtual Array 7100, or the
HP Virtual Array 74xx series high-performance, high-availability, multi-terabyte storage
arrays. One- and two-array configurations are supported.

Logical Storage

Virtual Array

The term "Virtual Array" refers to the way the disks within the array are treated as a pool of
data storage blocks instead of real physical disks.
Because data is spread across all of the disks in the array, logical-to-physical data maps keep
track of where the data is physically located on the disks in the array. These maps are stored in
array controller cache memory. The host has no visibility of the cache data maps; it is simply
presented with logical units (LUNs) for data storage operations.

Logical Unit Number

A logical unit number (LUN) is a logical aggregation of space on physical drives. LUNs are
unique identifiers that enable the controller to differentiate between separate devices (each of
which is a logical unit). Each LUN is a unique number that identifies a specific unit of storage.
The NAS 8000 supports up to 128 LUNs in single-array dedicated-storage configurations and
as little as 31 LUNs in FC-attach multiple-array configurations.

Volume Groups

A volume group is the aggregation of one or more LUNs. Volume groups combine the space
from LUNs and make the space accessible to the file system for creating file volumes and
directories, which can then be made accessible to users.
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Physical storage refers to the hardware you use for data storage.
Logical storage is created by software that organizes your physical storage into file
volumes and directories that are made accessible to users.
HP StorageWorks NAS 8000 Dedicated Storage High Availability, Solution Integration Manual (SIM)