1.1 Glossary

This document uses the following terms:

active partition: A partition on a master boot record (MBR) disk that becomes the system partition at system startup if the basic input/output system (BIOS) is configured to select that disk for startup. An MBR disk can have exactly one active partition. The active partition is stored in the partition table on the disk. GUID partitioning table (GPT) disks do not have active partitions. See also master boot record (MBR), system partition, and partition table.

allocation unit size: The size (expressed in bytes) of the units used by the file system to allocate space on a disk for the file system used by the volume. The size, in bytes, must be a power of two and must be a multiple of the size of the sectors on the disk. Typical allocation unit sizes of most file systems range from 512 bytes to 64 KB.

ASCII: The American Standard Code for Information Interchange (ASCII) is an 8-bit character-encoding scheme based on the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that work with text. ASCII refers to a single 8-bit ASCII character or an array of 8-bit ASCII characters with the high bit of each character set to zero.

basic disk: A disk on which each volume can be composed of exclusively one partition.

basic volume: A partition on a basic disk.

boot file: A file that contains a list of paths to boot partitions. On some systems, the boot file is stored on other nonvolatile media, such as nonvolatile random access memory (NVRAM)..

boot loader: An architecture-specific file that loads the operating system on the boot partition as specified by the boot configuration file.

boot loader file: See boot loader.

boot partition: A partition containing the operating system.

boot volume: See boot partition.

boot.ini: The name of the boot loader file on Windows–based computers.

bus: Computer hardware to which peripheral devices can be connected. Messages are sent between the CPU and the peripheral devices using the bus. Examples of bus types include SCSI, USB, and 1394.

bus type: A type of bus. Examples of bus types include SCSI, USB, and 1394.

Compact Disc File System (CDFS): A file system used for storing files on CD-ROMs.

Component Object Model (COM): An object-oriented programming model that defines how objects interact within a single process or between processes. In COM, clients have access to an object through interfaces implemented on the object. For more information, see [MS-DCOM].

crash dump file: A file that can be created by an operating system when an unrecoverable fault occurs. This file contains the contents of memory at the time of the crash and can be used to debug the problem creator.

cylinder: The set of disk tracks that appear in the same location on each platter of a disk.

disk: A persistent storage device that can include physical hard disks, removable disk units, optical drive units, and logical unit numbers (LUNs) unmasked to the system.

disk adapter: Computer hardware that controls a disk.

disk encapsulation: The process of converting a basic disk to a dynamic disk. Encapsulating a disk lays down disk metadata that is used for managing the disk dynamically.

disk extent: A contiguous set of one or more disk sectors. A disk extent can be used as a partition or part of a volume, or it can be free, which indicates that it is not in use or that it might be unusable for creating partitions or volumes.

disk group: In the context of dynamic disks, this term describes a logical grouping of disks.

disk group import: The act of merging a set of disks belonging to one disk group into another set of disks belonging to a second disk group. The result is a single disk group that includes all disks involved in the import.

disk regions: See disk extent.

disk signature: A unique identifier for a disk. For a master boot record (MBR)-formatted disk, this identifier is a 4-byte value stored at the end of the MBR, which is located in sector 0 on the disk. For a GUID partitioning table (GPT)-formatted disk, this value is a GUID stored in the GPT disk header at the beginning of the disk.

disk type: A disk that is hardware-specific. A disk can only communicate with the CPU using a bus of matching type. Examples of bus types include SCSI, USB, and 1394.

Distributed Component Object Model (DCOM): The Microsoft Component Object Model (COM) specification that defines how components communicate over networks, as specified in [MS-DCOM].

drive letter: One of the 26 alphabetical characters A-Z, in uppercase or lowercase, that is assigned to a volume. Drive letters serve as a namespace through which data on the volume can be accessed. A volume with a drive letter can be referred to with the drive letter followed by a colon (for example, C:).

dynamic disk: A disk on which volumes can be composed of more than one partition on disks of the same pack, as opposed to basic disks where a partition and a volume are equivalent.

dynamic volume: A volume on a dynamic disk.

extended partition: A construct that is used to partition a disk into logical units. A disk can have up to four primary partitions or up to three primary partitions and one extended partition. The extended partition can be further subdivided into multiple logical drives.

extent: A contiguous area of storage in a computer file system, reserved for a file.

FAT file system: A file system used to organize and manage files. The file allocation table (FAT) is a data structure that the operating system creates when a volume is formatted by using FAT or FAT32 file systems. The operating system stores information about each file in the FAT so that it can retrieve the file later.

FAT32 file system: A derivative of the file allocation table (FAT) file system. FAT32 supports smaller cluster sizes and larger volumes than FAT, which results in more efficient space allocation on FAT32 volumes. FAT32 uses 32-bit addressing.

fault-tolerant: The ability of computer hardware or software to ensure data integrity when hardware failures occur. Fault-tolerant features appear in many server operating systems and include mirrored volumes and RAID-5 volumes. A fault-tolerant volume maintains more than one copy of the volume's data. In the event of disk failure, a copy of the data is still available.

fault-tolerant mirror set: A volume configuration such that more than one copy of the volume data is maintained. Each copy of the data is placed on separate sets of disks. If a disk in one disk set fails, the volume's data is still available on the second set of disks.

file allocation table (FAT): A data structure that the operating system creates when a volume is formatted by using FAT or FAT32 file systems. The operating system stores information about each file in the FAT so that it can retrieve the file later.

file allocation units: Units of a specific size that are used by the file system to allocate space on a disk for the file system used by the volume.

file system: A system that enables applications to store and retrieve files on storage devices. Files are placed in a hierarchical structure. The file system specifies naming conventions for files and the format for specifying the path to a file in the tree structure. Each file system consists of one or more drivers and DLLs that define the data formats and features of the file system. File systems can exist on the following storage devices: diskettes, hard disks, jukeboxes, removable optical disks, and tape backup units.

file system flags: A set of values used by a file system to configure and report file system features and operations.

flags: A set of values used to configure or report options or settings.

foreign: A dynamic disk group that is not part of a machine's primary disk group. The term foreign denotes "foreign to this machine". Foreign disk and foreign disk groups are not online. This means that these disks may not be configured and no data input/output (I/O) to the disks or the volumes on the disks is permitted.

format: To submit a command for a volume to write metadata to the disk, which is used by the file system to organize the data on the disk. A volume is formatted with a specific file system.

free space: Space on a disk not in use by any volumes, primary partitions, or logical drives.

full format: A format in which all data sectors for the volume are initialized at the time the file system metadata is created.

globally unique identifier (GUID): A term used interchangeably with universally unique identifier (UUID) in Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the value. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the GUID. See also universally unique identifier (UUID).

GUID partition table (GPT): A disk-partitioning scheme that is used by the Extensible Firmware Interface (EFI). GPT offers more advantages than master boot record (MBR) partitioning because it allows up to 128 partitions per disk, provides support for volumes up to 18 exabytes in size, allows primary and backup partition tables for redundancy, and supports unique disk and partition IDs through the use of globally unique identifiers (GUIDs). Disks with GPT schemes are referred to as GPT disks.

hard disk physical name: An implementation-specific path that can be used to refer to a specific hard disk on a machine.

hibernation image: An image that contains metadata required to support a Windows operating system feature known as hibernation. Hibernation allows a system's state to be preserved in persistent storage while the system is shut down.

Integrated Drive Electronics (IDE) bus: A standard electronic interface used between a computer motherboard's bus and the computer's disk storage devices.

locked partition: A partition that is inaccessible.

Logical Disk Manager (LDM): A subsystem of Windows that manages dynamic disks. Dynamic disks contain a master boot record (MBR) at the beginning of the disk, one LDM partition, and an LDM database at the end. The LDM database contains partitioning information used by the LDM.

logical drive: A set of disk extents that compose a volume.

logical partition: See logical drive.

mass storage device: Any hardware device that provides persistent storage of data.

master boot record (MBR): Metadata such as the partition table, the disk signature, and the executable code for initiating the operating system boot process that is located on the first sector of a disk. Disks that have MBRs are referred to as MBR disks. GUID partitioning table (GPT) disks, instead, have unused dummy data in the first sector where the MBR would normally be.

Microsoft Interface Definition Language (MIDL): The Microsoft implementation and extension of the OSF-DCE Interface Definition Language (IDL). MIDL can also mean the Interface Definition Language (IDL) compiler provided by Microsoft. For more information, see [MS-RPCE].

mirrored volume: A fault-tolerant volume that maintains two or more copies of the volume's data. In the event that a disk is lost, at least one copy of the volume's data remains and can be accessed.

modification sequence number: An implementation-defined value for objects such as disks, volumes, drive letters, partitions, and regions that increases monotonically each time a configuration operation takes place on the object.

mount path: See mounted folder.

mount point: See mounted folder.

mounted folder: A file system directory that contains a linked path to a second volume. A user can link a path on one volume to another. For example, given two volumes C: and D:, a user can create a directory or folder C:\mountD and link that directory with volume D:. The path C:\MountD can then be used to access the root folder of volume D:.

NT file system (NTFS): A proprietary Microsoft file system. For more information, see [MSFT-NTFS].

object identifier (OID): In the context of an object server, a 64-bit number that uniquely identifies an object.

online: An operational state applicable to volumes and disks. In the online state, the volume or disk is available for data input/output (I/O) or configuration.

page file or paging file: A file that is used by operating systems for managing virtual memory.

partition: In the context of hard disks, a logical region of a hard disk. A hard disk may be subdivided into one or more partitions.

partition table: An area of a disk that is used to store metadata information about the partitions on the disk. See also, GUID partitioning table (GPT).

partition type: A value indicating the partition's intended use, or indicating the type of file system on the partition. For example, partition type 0x07 indicates that the partition is formatted with the NTFS file system. Original equipment manufacturers can designate a partition type of 0x12 to indicate that manufacturer-specific data is stored on the partition.

path: When referring to a file path on a file system, a hierarchical sequence of folders. When referring to a connection to a storage device, a connection through which a machine can communicate with the storage device.

primary disk group: In the context of dynamic disk, it is the disk group whose disks are online, which means they are accessible for input/output (I/O) and configuration. Each machine can have only one primary disk group. Disks on the machine belonging to other disk groups are referred to as "foreign disks" and their disk group is referred to as a "foreign disk group".

primary partition: A type of partition on a master boot record (MBR)-formatted disk.

quick format: A formatting that does not zero the data sectors on the volume at the time the file system metadata is created.

RAID-5: A fault-tolerant volume that maintains the volume's data across multiple RAID columns. Fault tolerance is provided by writing parity data for each stripe. In the event that one disk encounters a fault, that disk's data can be reconstructed using the parity data located on the other disks.

redundant arrays of independent disks (RAID): A set of disk-organization techniques that is designed to achieve high-performance storage access and availability.

region: See disk extent.

region flags: A set of values that describes the region's state or use.

region's status: The status of the region, such as whether the region is performing properly or encountering disk faults.

remote procedure call (RPC): A communication protocol used primarily between client and server. The term has three definitions that are often used interchangeably: a runtime environment providing for communication facilities between computers (the RPC runtime); a set of request-and-response message exchanges between computers (the RPC exchange); and the single message from an RPC exchange (the RPC message).  For more information, see [C706].

removable media: Any type of storage that is not permanently attached to the computer. A persistent storage device stores its data on media. If the media can be removed from the device, the media is considered removable. For example, a floppy disk drive uses removable media.

RPC protocol sequence: A character string that represents a valid combination of a remote procedure call (RPC) protocol, a network layer protocol, and a transport layer protocol, as described in [C706] and [MS-RPCE].

SCSI logical unit number (LUN): See logical unit number (LUN).

SCSI port number: A number that uniquely identifies a port on a small computer system interface (SCSI) disk controller. Each SCSI disk controller can support multiple SCSI bus attachments or ports for connecting SCSI devices to a computer.

sector: The smallest addressable unit of a disk.

serial storage architecture (SSA) bus: Serial storage architecture (SSA) is a standard for high-speed access to high-capacity disk storage. An SSA bus is implemented to the SSA standard.

simple volume: A volume whose data exists on a single partition.

small computer system interface (SCSI) bus: A standard for connecting peripheral devices to a computer. A SCSI bus is an implementation of this standard.

system directory: A directory that contains system files comprising the operating system.

system partition: A partition that contains the boot loader needed to invoke the operating system on the boot partition. A system partition must also be an active partition. It can be, but is not required to be, the same partition as the boot partition.

track: Any of the concentric circles on a disk platter over which a magnetic head (used for reading and writing data on the disk) passes while the head is stationary but the disk is spinning. A track is subdivided into sectors, upon which data is read and written.

Unicode: A character encoding standard developed by the Unicode Consortium that represents almost all of the written languages of the world. The Unicode standard [UNICODE5.0.0/2007] provides three forms (UTF-8, UTF-16, and UTF-32) and seven schemes (UTF-8, UTF-16, UTF-16 BE, UTF-16 LE, UTF-32, UTF-32 LE, and UTF-32 BE).

unique identifier (UID): A pair consisting of a GUID and a version sequence number to identify each resource uniquely. The UID is used to track the object for its entire lifetime through any number of times that the object is modified or renamed.

Universal Disk Format (UDF): A type of file system for storing files on optical media.

universal serial bus (USB): An external bus that supports Plug and Play installation. It allows devices to be connected and disconnected without shutting down or restarting the computer.

universally unique identifier (UUID): A 128-bit value. UUIDs can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects in cross-process communication such as client and server interfaces, manager entry-point vectors, and RPC objects. UUIDs are highly likely to be unique. UUIDs are also known as globally unique identifiers (GUIDs) and these terms are used interchangeably in the Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the UUID. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the UUID.

user-defined function (UDF): A function that is coded in a Microsoft Visual Basic for Applications (VBA) module, macro sheet, add-in, or Excel Linked Library (XLL). A UDF can be used in formulas to return values to a worksheet, similar to built-in functions.

volume: A group of one or more partitions that forms a logical region of storage and the basis for a file system. A volume is an area on a storage device that is managed by the file system as a discrete logical storage unit. A partition contains at least one volume, and a volume can exist on one or more partitions.

volume data: Data stored on a volume.

volume label: See file system label.

volume manager: A system component that manages communication and data transfer between applications and disks.

volume members: See RAID column.

volume plex: A member of a volume that represents a complete copy of data stored. For instance, mirrored volumes have more than one plex.

MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.