| ### RDN See Relative Distinguished Name. ### read access An access right that grants the ability to view CDS data. ### read-only fileset DFS: A fileset created by replicating a read/write fileset. A read-only fileset is also referred to as a read-only replica or a read-only version. See also backup fileset, read/write fileset. ### read-only replica A copy of a CDS directory in which applications cannot make changes. Although applications can look up information (read) from it, they cannot create, modify, or delete entries in a read-only replica. Read-only replicas become consistent with other, modifiable replicas of the same directory during skulks and routine propagation of updates. ### read/write fileset DFS: The single version of a fileset that houses the modifiable versions of files and directories. The read/write fileset is the original version for which an FLDB entry is allocated. It serves as the source fileset for its associated read-only and backup filesets. It is also referred to as the read/write source or read/write version. See also backup fileset, read-only fileset. ### read/write mount point DFS: A type of mount point that instructs the Cache Manager to access only the exact fileset specified in the mount point, not its read-only version. See also mount point, regular mount point. ### realm A cell, considered exclusively from the point of view of security; this term is used in Kerberos specifications. In DCE documentation, the term cell designates the basic unit of DCE configuration and administration, and incorporates the notion of a realm. ### recurring attribute An attribute with several attribute values. ### reentrant service A service that is safe to call from multiple threads in parallel. If a service is reentrant, there is no burden placed on calling routines to serialize their access or take other explicit precautions. See also thread_serial service, thread-synchronous service. ### reference monitor Code that controls access to an object. In DCE, servers control access to the objects they maintain; and for a given object, the ACL Manager associated with that object makes authorization decisions concerning the object. ### reference pointer RPC: A non-null pointer whose value is invariant during a remote procedure call and cannot point at aliased storage. ### referral An outcome that can be returned by a DSA that cannot perform an operation itself. The referral identifies one or more other DSAs more able to perform the operation. ### register RPC: To list an RPC interface with the RPC runtime. RPC: To place server-addressing information into the endpoint map. RPC: To insert authorization and authentication information into binding information. See also endpoint map , RPC interface . ### Registry database A database of information about persons, groups, organizations, and accounts. ### registry object A data node in the Registry database. Registry objects are of the following object types: principal, group, org, directory, policy, replist (replica list), and xattrschema. There are many nodes of the principal, group, org and directory types. There is only one node each for the policy, replist and xattrschema types. ### Registry replica A read-only instance of a Registry database. ### Registry Service One of three services provided by DCE Security; the Registry Service manages account information for principals. The other services are the Privilege Service and the Authentication Service. ### regular mount point DFS: The most common type of mount point. If the fileset it names is a read/write fileset, the Cache Manager is free to access a read-only version of the fileset (if one exists). See also mount point, read/write mount point. ### Relative Distinguished Name (RDN) A set of Attribute Value Assertions (AVAs), each of which is true, concerning the distinguished values of a particular entry. ### relative time A discrete time interval that is usually added to or subtracted from an absolute time. ### Release Replication DFS: A method of updating read-only copies of filesets. Release Replication is not automatic like Scheduled Replication; each update must be initiated by an administrator. See also replication, Scheduled Replication. ### remote procedure RPC: An application procedure located in a separate address space from the calling code. See also Remote Procedure Call. ### Remote Procedure Call (RPC) RPC: A procedure call executed by an application procedure located in a separate address space from the calling code. See also remote procedure . ### replica CDS: a copy of a directory in the CDS namespace. The first instance of a directory in the namespace is the master replica. When CDS managers make copies of the master replica to store in other clearinghouses, all of the copies, including the master replica, become part of the directory's replica set. See also read-only replica. DFS: A read-only copy of a fileset that contains all the data of the source fileset. As a full copy of a fileset, a replica can exist on any aggregate. A replica is different from a clone, which can reside only on the same aggregate as the source fileset. See also clone. Security: An instance of the Security Server and its database. One replica, the master replica, can accept updates and queries to its database. The slave replica can accept only queries. ### replica set The set of all copies of a CDS directory. Information about a directory's replica set is contained in an attribute of directories and child pointers called CDS_Replicas. The attribute contains the type of each replica (master or read-only) and the clearinghouse where it is located. When skulking a directory, CDS refers to the directory's replica set to ensure that it finds all copies of that directory. During a lookup, CDS can refer to the replica set in a child pointer when trying to locate a directory that does not exist in the local clearinghouse. ### replication CDS: Making a copy of a CDS directory in another clearinghouse. Replication can improve availability and load sharing. See also replica. GDS: The process by which copies of objects are created and maintained. DFS: The process of creating read-only copies of a fileset. In DFS, there are two types of replication: Release Replication and Scheduled Replication. Replication is supported only for DCE LFS filesets. See also Release Replication, Scheduled Replication. ### Replication Server DFS: A server process used in Release Replication and Scheduled Replication. The Replication Server tracks the currency of read-only replicas of filesets. It updates each replica to match its read/write source fileset as appropriate. See also replication. ### request buffer RPC: A first-in, first-out queue where an RPC system temporarily stores call requests that arrive at an endpoint of an RPC server, until the server can process them. ### restore DFS: The translation of a previously dumped fileset back into fileset format and its eventual replacement in the file system. The DFS Backup System allows several different types of restores, including full restores and date-specific restores. The operation need not involve recovery from other media such as tapes. See also date specific restore , dump, full restore. ### return value A function result that is returned in addition to the values of any output or input/output arguments. ### RPC See also Remote Procedure Call, DCE Remote Procedure Call. ### RPC control program RPC: An interactive management facility for managing name service entries and endpoint maps for RPC applications. The program is started by the rpccp command. ### RPC Daemon (rpcd) RPC: The process that provides the endpoint map service for a system. The RPC Daemon is started by the rpcd command. See also endpoint map, endpoint map service. ### RPC interface RPC: A logical grouping of operation, data type, and constant declarations that serves as a network contract for calling a set of remote procedures. See also interface definition. ### RPC protocol RPC: An RPC-specific communications protocol that supports the semantics of the DCE RPC API and runs over either connectionless or connection-oriented communications protocols. ### RPC protocol sequence RPC: A valid combination of communications protocols represented by a character string. Each protocol sequence typically includes three protocols: a network protocol, a transport protocol, and an RPC protocol that works with those network and transport protocols. See also network protocol , RPC protocol , transport protocol. ### RPC runtime RPC: A set of operations that manages communications, provides access to the name service database, and performs other tasks, such as managing servers and accessing security information, for RPC applications. See also RPC runtime library. ### RPC runtime library RPC: Routines of the RPC runtime that support the RPC applications on a system. The runtime library provides a public interface to application programmers, the Application Programming Interface (API), and a private interface to stubs, the Stub Programming Interface (SPI). See also RPC runtime. ### RPC thread RPC: A logical thread within which a remote procedure call executes. See also thread. ### rpcd See RPC Daemon. ### rundown procedure RPC: A procedure, typically used with a context handle, that is called following a communications failure to recover resources reserved by a server for servicing requests by a particular client. See also context handle.