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2-2-4 Other Management Functions

(1) Data management

Data management is a function that provides a method to access data stored on an auxiliary storage device through an interface that does not depend on the auxiliary storage device. In order to use data, it is necessary to consider physical aspects, such as the characteristics of the auxiliary storage device and the data recording method. However, a user cannot use a computer easily if it is necessary to think about this. Hence, the role of data management is to allow the user to manipulate data without the need to be aware of such matters. Data management manages file organization format and access methods. The details of file organization format and access methods are explained in section 4.

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(2) Input/output management

Input/output management performs tasks such as entering data to be processed by a computer and controlling input/output devices in order to obtain output of processing results. Upon a request for input/output (SVC interrupt), processing according to the input/output control method (e.g., in the case of channel control, sending a channel program to the input/output channel) is performed. Upon completion of input/output, notification of completion of input/output is performed with an input/output interrupt. Furthermore, in some cases, the role of input/output management includes a function that expands the concept of input/output devices and provides interfaces with peripheral devices that use device drivers or such other programs.

(3) Network management

Network management is a function that performs network control in relation to communication. It uses a network control program to provide an interface to connect to a LAN (Local Area Network) or a WAN (Wide Area Network). It also performs protocol control that uses communications protocols (e.g., OSI basic reference model, TCP/IP) and message control, which manages the order of data transactions and such other functions. “Network” is explained in detail in Chapter 5.

(4) Operations management

Operations management is a function that performs management of a computer system’s operational status from system startup processing (i.e., OS initialization) to system shutdown processing. It provides support for the effective use of a system, such as operation scheduling and creation of records through the monitoring of various information (e.g., usage status of system resources, billing information), and achieves simplicity and flexibility in operation. In some cases, the functions for user management described later are included in operations management.

(5) User management

User management is a function that issues a user ID for each user, and provides functions, such as profile function that saves user information and system environments and account function. Accounts in account functions refer to “rights.” Many rights are required in order to use a computer (or a system) such as the right to use a system, access rights for using data (of

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note, the rights regarding files are called file access rights) and rights to use a terminal. The setting/changing/deletion of such rights for each user is called account management. The user ID (and password) that is used to identify a user for performing such actions is sometimes called a user account (i.e., rights granted to users). In addition to general users, types of user accounts include a superuser (also known as an administrator in Windows-family OSs and a root in Unix-family OSs) that has administrator privileges (i.e., full rights) for a computer or a system, and a guest that signifies a temporary user. Furthermore, in some cases a directory service is used to share a user account across all terminals connected to a system. A directory service is a database service for the centralized management of resource information over a network, and the LDAP (Lightweight Directory Access Protocol) is commonly used for access.

(6) Security management

Security management is a function that maintains the confidentiality, integrity, and availability of information in order to maintain the security of a computer. Controls that apply to this include: access control which prohibits unauthorized access to resources with the account functions of user management, encryption control which encrypts recorded data to prevent information leakage, and controls to detect and prevent unauthorized intrusion from external locations. In order to confirm that these security controls are functioning effectively, it is verified as a reliability process that accountability is secured, through functions such as a logging function which records the history (i.e., log) of usage, and an audit function which inspects (i.e., audits) events such as login and logout. Chapter 6 explains the details of security.

(7) Fault management

Fault management is a function that monitors hardware and software, and takes measures at the occurrence of a fault. It covers both hardware faults that are caused by hardware problems and software faults that are caused by software problems. Depending on the fault, the appropriate measure, such as isolation of the area where the fault occurred and reconstruction of the system, or restart of the system, is implemented. Furthermore, by recording in advance the fault status, cause, and measures when a malfunction occurs, this can be used to reduce the recovery time (i.e., MTTR) when the same type of fault occurs.