Standard Architecture (EISA) bus. ISA and EISA boards plug into an IA or EISA slot, while
polling delay. The time in seconds between successive discovery processes during which discovery is inactive.
port. A part of the system unit or remote controller to which cables for external devices (such as display stations, terminals, printers, switches, or external storage units) are attached. The port is an access point for data entry or exit. A device can contain one or more ports.
portable document format (PDF). A standard specified by Adobe Systems, Incorporated, for the electronic distribution of documents. PDF files are compact; can be distributed globally by
premium feature key. A file that the storage subsystem controller uses to enable an authorized premium feature. The file contains the feature enable identifier of the storage subsystem for which the premium feature is authorized, and data about the premium feature. See also feature enable identifier.
private loop. A freestanding arbitrated loop with no fabric attachment. See also arbitrated loop.
program temporary fix (PTF). A temporary solution or bypass of a problem diagnosed by IBM in a current unaltered release of the program.
PTF. See program temporary fix.
RAID. See redundant array of independent disks (RAID).
RAID level. An array's RAID level is a number that refers to the method used to achieve redundancy and fault tolerance in the array. See also array, redundant array of independent disks (RAID).
RAID set. See array.
RAM. See random-access memory.
RDAC. See redundant disk array controller.
recoverable virtual shared disk (RVSD). A virtual
shared disk on a server node configured to provide continuous access to data and file systems in a cluster.
redundant array of independent disks (RAID). A collection of disk drives (array) that appears as a single volume to the server, which is fault tolerant through an assigned method of data striping, mirroring, or parity checking. Each array is assigned a RAID level, which is a specific number that refers to the method used to achieve redundancy and fault tolerance. See also array, parity check, mirroring, RAID level, striping.
redundant disk array controller (RDAC). (1) In hardware, a redundant set of controllers (either active/passive or active/active). (2) In software, a layer that manages the input/output (I/O) through the active controller during normal operation and transparently reroutes I/Os to the other controller in the redundant set if a controller or I/O path fails.
remote mirroring. Online,
ROM. See read-only memory.
router. A computer that determines the path of network traffic flow. The path selection is made from several paths based on information obtained from specific protocols, algorithms that attempt to identify the shortest or best path, and other criteria such as metrics or
RVSD. See recoverable virtual shared disk.
SAI. See Storage Array Identifier.
SA Identifier. See Storage Array Identifier.
SAN. See storage area network.
SATA. See serial ATA.
scope. Defines a group of controllers by their Internet Protocol (IP) addresses. A scope must be created and defined so that dynamic IP addresses can be assigned to controllers on the network.
SCSI. See small computer system interface.
segmented loop port (SL_port). A port that allows division of a
sense data. (1) Data sent with a negative response, indicating the reason for the response. (2) Data describing an I/O error. Sense data is presented to a host system in response to a sense request command.
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