LVM Migration from Legacy to Agile Naming Model

Glossary
Active/Active device
An active/active device has two or more ports to the same LUN, both of which can be accessed
simultaneously.
Active/Passive device
Also known as asymmetric active/active device. Though the same LUN has multiple ports, unlike an
active/active device, only the primary port should be used for LUN access at any time.
Agile Addressing
The ability to address a LUN with the same device special file regardless of the physical location of the
LUN or the number of paths leading to it. The DSF for a LUN remains the same even if the LUN is moved
from one HBA to another, moved from one switch or hub port to another, presented using a different
target port to the host, or configured with multiple hardware paths. This is also referred to as persistent
LUN binding.
Agile View
The representation of LUNs using lunpath hardware paths, LUN hardware paths, and persistent DSFs,
introduced in HP-UX 11i v3.
Legacy DSF
A DSF with the hardware path information such as SCSI bus, target, and LUN embedded in the file’s
minor name and file name, such as /dev/dsk/c2t3d4.
Legacy Naming Model
The representation of legacy hardware paths and legacy DSFs as in releases prior to HP-UX 11i v3.
DSF
Device Special File. A file associated with an I/O device. DSFs are read and written the same as
ordinary files, but requests to read, write or control are sent to the associated device.
Hardware Path
A series of numbers representing the physical or virtualized location of a device. The path is a sequence
of I/O addresses that share a hierarchical relationship. The address elements may not correspond to
physical hardware addresses, and may represent only a “handle” to a device rather than a physical path
to it.
LUN
A SCSI logical unit. This refers to an end storage device such as a disk, tape, floppy, or CD. This is the
logical unit itself and does not represent the path to the logical unit.
Lunpath
The physical hardware path leading to a SCSI logical unit. A SCSI LUN can have more than one lunpath.
Multi-Pathing
The detection, correlation, and coordinated usage of multiple hardware paths leading to the same LUN.
Persistent DSF
A DSF conforming to the naming model introduced in HP-UX 11i v3 to support agile addressing. The
device file name contains an instance number, such as /dev/disk/disk10, and the minor number has
no hardware path information.
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