HP-UX 11i v3 Installation and Update Guide, September 2007 (Update 1 Release)

Mass Storage Stack for HP-UX 11i v3
HP-UX 11i v3 introduces a new representation of mass storage devices, known as the
agile view. In the agile view, disk devices and tape drives are identified by the actual
object, not by a hardware path to the object. In addition, paths to the device can change
dynamically and multiple paths to a single device can be transparently treated as a
single virtualized path, with I/O being distributed across those multiple paths.
This representation increases the reliability, adaptability, performance, and scalability
of the mass storage stack, without the need for operator intervention.
HP-UX 11i v3 Hardware Paths
In HP-UX 11i v3, there are three different types of paths to a device: legacy hardware
path, lunpath hardware path, and LUN hardware path. All three are numeric strings
of hardware components, with each number typically representing the location of a
hardware component on the path to the device. These paths are described below.
• Legacy hardware path The legacy hardware path is the format used in releases
prior to HP-UX 11i v3, and is displayed in the legacy view. It is composed of a
series of bus-nexus addresses separated by '/' leading to the host bus adapter (HBA);
beyond the HBA, additional address elements are separated by '.'.
• Lunpath hardware path
The lunpath format enables the use of more targets and LUNs than are permitted
under legacy hardware paths, and is printed in the agile view. It is identical in
format to a legacy hardware path, up to the HBA (and represents the same path
to the LUN). Beyond the HBA, additional elements are printed in hexadecimal.
• LUN hardware path
The LUN format is a virtualized path that represents all the lunpaths to a single
LUN. It is printed in the agile view. Instead of a series of bus-nexus addresses
leading to the HBA, the path contains a virtual bus-nexus (referred as the virtual
root node) with an address of 64000. An example of a LUN hardware path is
64000/0xfa00/0x22.
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