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PaaS	[Services] Shorthand for Platform as a Service.
panic	[Computer System] A colloquial term describing a software program's reaction to an incomprehensible state.
parallel transmission	[Network] Simultaneous transmission of multiple data bits over multiple physical lines.
parity data	[Storage System] In a RAID array, data stored on member drives that can be used for regenerating any user data that becomes inaccessible.
parity drive	[Storage System] In a RAID 3 array or RAID 4 array and some RAID 6 arrays, a dedicated drive on which parity data is stored.
partition	[Storage System] 1. A subdivision of the capacity of a physical disk or virtual disk. 2. A contiguously addressed range of logical blocks on a physical media that is identifiable by an operating system. Partitions are consecutively numbered ranges of blocks that are created and used by Windows and most UNIX operating systems.
partitioning	[Storage System] Presentation of the usable storage capacity of a drive or array to an operating environment in the form of several virtual drives. The aggregate capacity of the partitions of a drive approximates the capacity of the underlying physical drive or virtual drive. Partitioning is common in modern operating systems.
passphrase	[Data Security] A sequence of characters longer than the typical length of a password.
password	[Data Security] A private alphanumeric string used to authenticate an identity.
password digest	[Data Security] The hashed form of a cleartext password.
path	[Network], [Computer System], [Storage System], [Cloud], [File System] [Storage System] The access path from a host computer to a storage device. [File System] The combination of device address and file system directory elements used to locate a file within a file system. [Network] Any route through an interconnect that allows two devices to communicate. [Computer System] A sequence of computer instructions that performs a given function, such as I/O request execution. [Cloud] The access path from an internet-connected computer to a cloud service endpoint, typically in the form of a URI or URL.
path length	[Computer System], [File System] [Computer System] The number of instructions (a rough measure of the amount of time) required by a computer to perform a specific activity, such as I/O request execution. [File System] The number of characters in a path name.
path name	[File System] The complete list of nested sub-directories through which a file is reached.
payload	[Network], [Fibre Channel] [Network] Contents of the data field of a communication frame or packet. [Fibre Channel] The user data contained in a frame, excluding optional headers and fill bytes, if present.
PB	[Computer System] Shorthand for Petabyte (1015 bytes).
PBA	[Storage System] Shorthand for physical block address.
Pbit	[General] Shorthand for petabit.
Pbyte	[Computer System] Shorthand for petabyte (1015 bytes).
PCI	[Computer System] Shorthand for Peripheral Component Interconnect
PCI Express Queuing Interface	[SCSI], [Standards] A standard describing a circular queue interface for transferring information between a host and a device on a PCI Express bus or fabric.
PCI Express®	[Computer System] High speed interconnect specification developed and maintained by PCI-SIG.
PCI-SIG®	Shorthand for Peripheral Component Interconnect Special Interest Group. This is the commonly used term for this organization.
PCIe®	[Computer System] An acronym for Peripheral Component Interconnect Express.
pcnfsd	[File System] A daemon that permits personal computers to access file systems via the NFS protocol.
PDU	[Network], [Computer System] 1. [Network] Acronym for Protocol Data Unit. 2. [Computer System] Acronym for Power Distribution Unit.
pebibit	[General] Shorthand for 1,125,899,906,842,624 (250) bits. Binary notation is most commonly used for semiconductor memory sizes. See also petabit.
Pebibyte	[General] Shorthand for 1,125,899,906,842,624 (250) bytes. Binary notation is most commonly used for semiconductor memory sizes. See also Petabyte.
peer	[Computer System] One of multiple complementary but physically separate systems.
penetration	[Data Security] An unauthorized bypassing of the security mechanisms of a system.
penetration testing	[Data Security] A test methodology that attempts to circumvent or defeat the security features of an information system.
penta-level cell	[Hardware] A memory cell that stores five bits of data.
performance audit	[Computer System] Systematic evaluation of a system by assessing how well it conforms to a set of established performance criteria.
Peripheral Component Interconnect	[Computer System] A set of standards for buses connecting interface modules to a computer system. Older variations of the PCI standards support 32 bit and 64 bit parallel data transfers at 33 MHz and 66 MHz rates. The newer PCIe standards support one bit wide serial "lanes" operating at various data rates (e.g., 250MB/sec or 500MB/sec). See PCI-SIG.
Peripheral Component Interconnect Special Interest Group	An organization responsible for developing the family of PCI™ specifications and PCIe® specifications. The commonly used term for this organization is PCI-SIG®.
Permanent Port Name	[Fibre Channel] The Name_Identifier common among all VN_Ports that are associated with the PN_Port, and is set to the F_Port_Name of the F_Port that is attached to the physical interface.
persistence	[Computer System] A synonym for non-volatility, usually used to distinguish between data and metadata held in DRAM, which is lost when electrical power is lost, and data held on non-volatile storage (disk, tape, battery-backed DRAM, etc.) that survives, or persists across power outages.
persistent memory	[Computer System] Non-volatile, byte addressable, low latency memory.
persistent memory access model	[Computer System] Semantic definition of how software accesses persistent memory hardware
persistent memory hardware	[Computer System] NVRAM that is byte addressable.
Personally Identifiable Information	[Data Security] Information associated with a person, as defined in ISO/IEC 29100.
petabit	[General] Shorthand for 1,000,000,000,000,000 (1015) bits. The base 10 convention is commonly found in I/O-related and scientific literature; the base 2 convention (1,125,899,906,842,624, i.e., 250) is commonly used for memory capacity. See also pebibit.
petabyte	[Computer System] Shorthand for 1,000,000,000,000,000 (1015) bytes. The base 10 convention is commonly found in I/O-related and scientific literature; the base 2 convention (1,125,899,906,842,624, i.e., 250) is commonly used for memory capacity. See also pebibyte.
PFC	[Network] Shorthand for Priority-based Flow Control.
phy	[Computer System] The component that connects a port to a physical link. The physical link may be electrical, optical, radio, or other.
physical block	[Storage System] A physical location on storage media where data is stored. A physical block is different from the logical block and virtual block typically presented to the operating environment by a storage device.
physical block address	[Storage System] A number that is associated with a physical block.
physical configuration	[General] 1. The installation, removal, or re-installation of disks, cables, HBAs, and other components required for a system or subsystem to function. 2. The combination of disks, cables, HBAs, and other components required for a system or subsystem to function.
physical disk	[Storage System], [Operating System] 1. [Storage System] A disk that is not virtual. 2. [Operating System] An online storage device that is visible to a host operating system.
physical extent	[Storage System] A number of physically consecutive blocks on a physical disk. Physical extents are created by control software as building blocks from which redundancy groups and volume sets are created. Called a p-extent by ANSI.
physical extent block number	[Storage System] The relative position of a block within a physical extent. Physical extent block numbers are used to develop higher-level constructs in RAID array striped data mapping, not for application or data addressing.
Pib	[General] Shorthand for 1,125,899,906,842,624 (250) bits. Binary notation is commonly used for semiconductor memory sizes. See also petabit.
Pibit	[General] Shorthand for Pebibit.
PiByte	[General] Shorthand for Pebibyte.
PII	[Data Security] Shorthand for Personally Identifiable Information.
PIT copy	[Data Recovery] Shorthand for point in time copy.
PKCS	[Data Security] Shorthand for Public Key Cryptography Standards.
PKI	[Data Security] Shorthand for Public Key Infrastructure.
plaintext	[Data Security] Unencrypted information.
platform	A physical entity that contains nodes. Platforms include all end devices that are attached to a Fabric, for example, hosts and storage subsystems. Platforms communicate with other platforms in the storage area network using the facilities of a Fabric or other topology
Platform as a Service	[Services] Delivery over a network of a virtualized programming environment, consisting of an application deployment stack based on a virtual computing environment. Typically, PaaS is based on IaaS, is either self-provisioned or provisionless, and is billed based on consumption.
PLC	[Hardware] Shorthand for Penta-Level Cell
PLOGI	[Fibre Channel] Acronym for N_Port Login.
PN_Port	[Fibre Channel] A Fibre Channel Link Control Facility that supports only Nx_Ports in a node.
point in time copy	[Data Recovery] A fully usable copy of a defined collection of data that contains an image of the data as it appeared at a single instant in time. A point in time copy is considered to have logically occurred at that point in time, but implementations may perform part or all of the copy at other times (e.g., via database log replay or rollback) as long as the result is a consistent copy of the data as it appeared at that point in time. See snapshot, copy on write, and pointer remapping.
point of encryption	[Data Security] Location within the Information and Communications Technology (ICT) infrastructure where data are encrypted on its way to storage (3.43) and, conversely, where data are decrypted when accessed from storage. [ISO/IEC 27040] The point of encryption is only applicable for data at rest.
pointer copy	[Data Recovery] A point in time copy made using the pointer remapping technique.
pointer remapping	[Data Recovery] A technique for maintaining a point in time copy such that when a logical data location is written, a new physical location is chosen for the updated data, and the pointer for that data is remapped to point to it. See Copy on Write.
Policy	[General], [Management] [General] A definite goal, course, or method of action to guide and determine present and future decisions. [Management] Policies as a set of rules to administer, manage, and control access to network resources. This definition reflects the definition in RFC 3198. Policies are implemented or executed within a particular context, such as policies defined within a business unit. See policy goal and policy rule. See RFC 3060.
policy goal	[Management] The objectives or desired state intended to be maintained by a policy system. This definition reflects the definition in RFC 3198. As the highest level of abstraction of policy, these goals are most directly described in business rather than technical terms. For example, a goal might state that a particular application operate on a network as though it had its own dedicated network, despite using a shared infrastructure. 'Policy goals' can include the objectives of a service level agreement, as well as the assignment of resources to applications or individuals. A policy system may be created that automatically strives to achieve a goal through feedback regarding whether the goal (such as a service level) is being met.
policy processor	[Computer System] The processor that schedules the overall activities in an intelligent device. Policy processors are usually augmented by additional processors, state machines, or sequencers that perform the lower-level functions required to implement overall policy.
policy rule	[Management] The binding of a set of actions to a set of conditions, where the conditions are evaluated to determine whether the actions are performed.
port	[Network] 1. An entrance to or exit from a storage network. 2. A connection point for a peripheral device or an application program. Ports can be logical, physical or both. Examples include Fibre Channel ports, Internet Protocol ports and SCSI ports.
port login	The port-to-port login process by which Fibre Channel initiators establish sessions with targets.
Port VF_ID	[Fibre Channel] A configurable VF-ID that is associated with any untagged frame received by a VF capable multiplexer.
Port_ID	[Fibre Channel] Shorthand for N_Port_ID.
Port_Name	[Fibre Channel] A Name-Identifier that is associated with a Fibre Channel port.
POST	[Computer System] Acronym for power-on self-test.
post-process data deduplication	[Storage System] Data deduplication performed after the data to be deduplicated has been initially stored. See inline data deduplication.
power conditioning	[General] The regulation of power supplied to a system so that acceptable ranges of voltage and frequency are maintained. Power conditioning is sometimes done by a storage subsystem, but may also be an environmental requirement.
power distribution unit	[Computer System] An element or device which distributes power to and possibly monitors the power consumption of other devices in a system.
power efficiency	[Computer System] Synonym for electrical efficiency.
power supply	[Computer System] A component which converts an AC or DC voltage input to one or more DC voltage outputs for the purpose of powering a system or subsystem. Power supplies may be redundant and hot swappable.
power supply efficiency	[Storage System] The efficiency of a power supply.
power supply unit	[Computer System] Synonym for power supply.
power-on self-test	[Computer System] A set of internally stored diagnostic programs run by intelligent devices when powered on, that verify the basic integrity of hardware before software is permitted to run on it.
PP	[Data Security] Acronym for Protection Profile.
PQI	[SCSI] Shorthand for PCI Express Queuing Interface.
preservation	[Data Management] The processes and operations involved in ensuring the ability to read, interpret, authenticate, secure and protect against the loss of data or information throughout its lifecycle.
preservation object	[Long-Term Retention] The basic unit of data or information that is preserved by a preservation system. The Archival Information Package (AIP) defined in Open Archival Information System (OAIS) is an example of a preservation object.
preservation system	[Long-Term Retention] A repository that, either as its sole responsibility or as one of multiple responsibilities, undertakes all necessary actions for the long-term preservation of the data or information in its custody.
Primary storage	[Data Management] Data storage device, system, or service used to store data that is accessed frequently by applications.
Primitive Sequence	[Fibre Channel] In an encoded data stream, an Ordered Set transmitted repeatedly and continuously until a specified response is received.
Primitive Signal	[Fibre Channel] In an encoded data stream, an Ordered Set with a special meaning such as an idle or Receiver_Ready (R_RDY).
Priority-based Flow Control	[Network] A Data Center Bridging (DCB) mechanism that provides link level flow control on a per-priority basis for full-duplex links.
privacy breach	[Data Security] Situation where personally identifiable information is processed in violation of one or more relevant privacy safeguarding requirements [source: ISO/IEC 29100:2011].
private cloud	[Services] Delivery of SaaS, PaaS, IaaS and/or DaaS to a restricted set of customers, usually within a single organization. Private Clouds are created due to issues of trust.
private key	[Data Security] The cryptographic key in an asymmetric cryptosystem that is not made public.
private key cryptography	[Data Security] An encryption methodology in which the encryptor and decryptor use the same key, which must be kept secret. See symmetric cryptosystem.
private loop	[Fibre Channel] A Fibre Channel Arbitrated Loop with no Fibre Channel Fabric attachment.
privilege	[Data Security] A right granted to an individual, a program, or a process. [source: CNSSI-4009]
privileged user	[Data Security] A user who, by virtue of function or seniority, has been allocated powers within a system that are significantly greater than those available to the majority of users. Such persons will include, for example, the system administrator(s), storage administrator(s), and network administrator(s) who are responsible for keeping the system available and may need powers to create new user profiles as well as add to or amend the powers and access rights of existing users.
process policy	[Fibre Channel] An error handling policy that allows a port to continue processing data frames following detection of one or more missing frames in a Sequence.
product under test	[Computer System] A system or component that is the subject of a test.
profile	[Standards] A proper subset of a standard or specification that supports interoperability across a set of products or in a specific application. A profile is a vertical slice through a standard or specification containing physical, logical and behavioral elements required for interoperability. A profile may make some optional features of a standard or specification mandatory or prohibited.
proprietary interconnect	[Computer System] An I/O interconnect or network interconnect whose transmission characteristics and/or protocols are not standardized and require the permission of the owner to be implemented. See standard interconnect.
protection profile	[Data Security] An implementation-independent set of security functional and assurance requirements for a category of IT products that meet specific consumer needs. Protection profiles (PP) are most commonly associated with ISO 15408.
protocol	[General] A set of rules that control an interaction between two or more entities in communication with one another. Rules may specify the formats of a set of communication messages, and in what sequences they are expected to occur. Examples of protocols include TCP/IP and Fibre Channel.
Protocol Data Unit	[Network] A single message between two network nodes used for communication.
provenance	[General] Information regarding an item's source, origin, custody and ownership.
provisioning	[Computer System] The process of initializing and equipping a system to provide services.
Proxy Fabric	[Fibre Channel] In an IFR environment, the remote Fibre Channel Fabric associated with a Proxy Nx_Port.
Proxy Nx_Port	A role of an Nx_Port in an IFR environment. From the perspective of a remote (Proxy) Fabric, an Nx_Port assumes the role of a Proxy Nx_Port.
PSU	[Computer System] Shorthand for power supply unit.
public cloud	[Services] Delivery of SaaS, PaaS, IaaS and/or DaaS to a relatively unrestricted set of customers.
public key	[Data Security] A cryptographic key that is made public for purposes of using asymmetric encryption with an entity that has the private key.
public key cryptography	[Data Security] Synonym for asymmetric cryptography.
Public Key Infrastructure	[Data Security] A collection of software, hardware, people and procedures that facilitate secure creation and management of digital certificates.
public loop	[Fibre Channel] A Fibre Channel Arbitrated Loop with an attachment to a Fibre Channel Fabric.
pull technology	[Computer System] The transmission of information in response to a request for that information. An example of a pull technology is polling. See push technology.
pulverization	[Data Security] A method of sanitization that reduces devices or components to fine particles of a specified size. Pulverization is related to shredding, but usually uses a grinding process as opposed to a cutting process. [ISO/IEC 27040]
purge	[Storage System], [Data Security] [Data Security] A class of sanitization that makes recovery infeasible using state of the art laboratory techniques, but which preserves the storage media in a potentially reusable state. [ISO/IEC 27040] [Storage System] The process of returning a solid state storage device to a state in which subsequent writes execute, as closely as possible, as if the device had never been used and does not contain any valid data. See FOB.
push technology	[Computer System] The transmission of information from a source or initiator without a request to the source to send that information. An example of a push technology is an SNMP trap. See pull technology.