HP StorageWorks 8000 NAS - Manual (Page 25)

NAS 8000 Concepts 23
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Logical Storage
The HP NAS 8000 lets you set up your storage into these logical divisions:
Logical Unit Number
A logical unit number (LUN) is a logical aggregation of the space on one or
more physical drives. The HP NAS 8000 supports a maximum of 127 LUNs.
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.
File Volumes
A volume group is divided into one or more file volumes. File volumes are the
basic unit of logical storage for a file system on the HP NAS 8000. File
volumes can be further subdivided into individual directories.
Directories
Directories let you organize information. Directories contain files or other
persistent data structures in a file system that contains information about other
files. Directories are usually organized hierarchically and may contain both
files and other directories, and are used to organize collections of files for
applications or convenience.
Snapshots
A snapshot is a read-only picture of a file volume at a specific point in time
that provides almost instantaneous access to the previous snapshot version of
a file.