installation and reference guide HP MPIO Full Featured DSM for MSA1000/1500 (Active-Active) Disk Arrays 3.02.00 (AA-RW8AF-TE, March 2009)

Glossary
This glossary defines the terms used in this guide or related to this product. It is not a comprehensive
glossary of computer terms.
controller A hardware device that facilitates communication between a host and one or
more LUNs organized as an array.
DSM Device Specific Module
fabric A network that contains high-speed fiber connections resulting from the
interconnection of switches and devices. A fabric is an active and intelligent
non-shared interconnect scheme for nodes.
failover The automatic substitution of a functionally equivalent system component for a
component that has failed.
HBA Host Bus Adapter. An I/O device that serves as the interface connecting a host
system to the SCSI bus or SAN (Storage Area Network)
host The computer system on which the Multipath software is running.
LUN Logical Unit Number. The actual unit number assigned to a device by the RAID
system controller.
mode A user-selectable parameter that specifies path behavior during normal and
failure conditions. Paths can be set to one of the following modes:
• Preferred — Indicates the path you choose for the desired I/O paths. When
a path is in preferred mode, load balance is not enabled and the Load Bal-
ance Type displays as none.
• Alternate — Indicates a path that is used for device access and I/O activities
when the preferred path fails.
MPIO Multipathing Input/Output.
path A virtual communication route that enables data and commands to pass between
a host server and a storage device.
path state An attribute that describes the operational condition of a path. A path can exist
in one of the following states:
• Active — Path is currently used for the I/O stream or is available for load
balancing.
• Available — Path is currently available, but not used for device access. The
path is only in this state when no load balancing policy has been selected
for the LUN.
• Standby — Intermediate state of the path before it is initialized (made ready
for device access), normally will not be seen.
HP MPIO Full Featured DSM for MSA1000/1500 (Active-Active) Disk Arrays 3.02.00 51