HP StorageWorks Sun Solaris Kit V3.0B for Enterprise Virtual Array Installation and Configuration Guide (AA-RUH4B-TE, October 2003)

Glossary
42 Sun Solaris Kit V3.0B for Enterprise Virtual Array Installation and Configuration Guide
physical disk
A disk drive mounted in a disk drive enclosure that communicates with a controller pair
through the device-side Fibre Channel loops. A physical disk is hardware with embedded
software, as opposed to a virtual disk, which is constructed by the controllers. Only the
controllers can communicate directly with the physical disks.
The physical disks, in aggregate, are called the array and constitute the storage pool from
which the controllers create virtual disks.
physical disk array
See array.
port
A Fibre Channel connector on a Fibre Channel device.
port_name
A 64-bit unique identifier assigned to each Fibre Channel port. The port_name is
communicated during the login and port discovery processes.
preferred path
A preference for which controller of the controller pair manages the virtual disk. This
preference is set by the user through the Command View EVA when creating the virtual
disk. A host can change the preferred path of a virtual disk at any time. The primary
purpose of preferring a path is load balancing.
read caching
A cache method used to decrease subsystem response times to a read request by allowing
the controller to satisfy the request from the cache memory rather than from the disk drives.
Reading data from cache memory is faster than reading data from a disk. The read cache is
specified as either on or off for each virtual disk. The default state is on.
read ahead caching
A cache management method used to decrease the subsystem response time to a read
request by allowing the controller to satisfy the request from the cache memory rather than
from the disk drives.
redundancy
■ Element Redundancy—The degree to which logical or physical elements are protected
by having another element that can take over in case of failure. For example, each loop
of a device-side loop pair normally works independently but can take over for the other
in case of failure.
■ Data Redundancy—The level to which user data is protected. Redundancy is directly
proportional to cost in terms of storage usage; the greater the level of data protection,
the more storage space is required.