Terms And Definitions of Mass Storage Devices

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Terms and Definitions of Mass Storage Devices

Terms                     Definitions

Agile addressing         

The Device File Name of the logical unit is independent of the paths leading to the LUN.

The ability to address a logical unit with the same device file regardless of the location of the LUN, i.e. The device file for a LUN remains the same even if the LUN is moved from one HBA to another, from one switch/hub port to another or presented via a different target port to the host.

Agile View of the I/O tree

View of the I/O Tree using agile addressing to represent elements of the I/O tree.

(Legacy) H/W Path

H/W Path in the legacy format. Used for all components, mass storage or not.

Legacy or agile I/O Tree

The I/O Tree is the HP-UX representation of physical and virtual devices discovered by the Operating System. The legacy I/O tree is limited to the legacy view. The agile I/O tree is limited to the agile view.


Logical unit that refers to an end storage device such as disk, tape, floppy, cdrom, changer, etc. This is the logical unit itself and does not represent the path to the logical unit.


I/O path to a LUN in agile format.

LUN id

This is the SCSI address of the LUN within the target as defined in the SCSI standard.

Agile naming model

DSF naming model introduced in HP-UX 11i v3 to support agile addressing.

Persistent DSF

DSF following the persistent naming model conventions. Does not contain any encoding of bus, target identifier or device specific option information.

legacy naming model / legacy format

Device special file format convention used prior to HP-UX 11i v3. This model is maintained in HP-UX 11i v3 for backward compatibility purpose.

(legacy) DSF

A path dependent device file, following the legacy naming model conventions, wherein the DSF embeds the bus/target/lun/option for a specific path to a mass storage device (Ex. /dev/dsk/c#t#d#).

SCSI class driver

A HP-UX device driver which manages one or more specific classes of mass storage devices. Ex : Disk Driver, Tape Driver, Changer Driver, Pass-thru Driver.

Target Id

Corresponds to the target port identifier as defined in SCSI transport protocols


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