1.1 Glossary

This document uses the following terms:

Alternate Data Stream: A named data stream that is part of a file or directory, which can be opened independently of the default data stream. Many operations on an alternate data stream affect only that stream and not other streams or the file or directory as a whole.

backup: The process of copying data to another storage location for safe keeping. This data can then be used to restore lost information in case of an equipment failure or catastrophic event.

cluster: The smallest allocation unit on a volume.

compression unit: A segment of a stream that the object store can compress, encrypt, or make sparse independently of other segments of the same stream.

Default Data Stream: The unnamed data stream in a non-directory file. Many operations on a default data stream affect the file as a whole.

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] have to be used for generating the GUID. See also universally unique identifier (UUID).

logical cluster number (LCN): The cluster number relative to the beginning of the volume. The first cluster on a volume is zero (0).

mount point: See mounted folder.

reparse point: An attribute that can be added to a file to store a collection of user-defined data that is opaque to NTFS or ReFS. If a file that has a reparse point is opened, the open will normally fail with STATUS_REPARSE, so that the relevant file system filter driver can detect the open of a file associated with (owned by) this reparse point. At that point, each installed filter driver can check to see if it is the owner of the reparse point, and, if so, perform any special processing required for a file with that reparse point. The format of this data is understood by the application that stores the data and the file system filter that interprets the data and processes the file. For example, an encryption filter that is marked as the owner of a file's reparse point could look up the encryption key for that file. A file can have (at most) 1 reparse point associated with it. For more information, see [MS-FSCC].

Restore: The act of copying data (usually files) back to its original storage location from some other storage media after some form of data loss.

security identifier (SID): An identifier for security principals that is used to identify an account or a group. Conceptually, the SID is composed of an account authority portion (typically a domain) and a smaller integer representing an identity relative to the account authority, termed the relative identifier (RID). The SID format is specified in [MS-DTYP] section 2.4.2; a string representation of SIDs is specified in [MS-DTYP] section 2.4.2 and [MS-AZOD] section 1.1.1.2.

server: A computer on which the remote procedure call (RPC) server is executing.

Software Defect Management: A mechanism for the object store to manage and remap defective blocks on removable rewritable media (such as CD-RW, DVD-RW, and DVD+RW). Only the UDFS file system supports Software Defect Management.

symbolic link: A symbolic link is a reparse point that points to another file system object. The object being pointed to is called the target. Symbolic links are transparent to users; the links appear as normal files or directories, and can be acted upon by the user or application in exactly the same manner. Symbolic links can be created using the FSCTL_SET_REPARSE_POINT request as specified in [MS-FSCC] section 2.3.81. They can be deleted using the FSCTL_DELETE_REPARSE_POINT request as specified in [MS-FSCC] section 2.3.5. Implementing symbolic links is optional for a file system.

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).

virtual cluster number (VCN): The cluster number relative to the beginning of the file, directory, or stream within a file. The cluster describing byte 0 in a file is VCN 0.

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.

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.