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Master–slave (technology)
In engineering, master–slave is a relationship between two systems in which one controls the other. In some cases one master controls just one slave system, but in others there are multiple slave systems controlled by the same master. Sometimes the master is a different kind of system than the slave, but sometimes there are multiple similar systems and one of them is designated the master in order to centralize external (i.e. user) control of the collection. Due to its connection to slavery, the terminology is a subject of controversy and has been replaced with alternative terms in some cases. Examples In photography, secondary, or slave, flash units are connected to a master unit to provide synchronized lighting. Parallel audio duplication often entails multiple recording with linkdevices (i.e. for cassette tape or compact disc) linked together so that operating the controls of a master device triggers the same commands on slave devices. Railway locomotives operating in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering
Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, systems. Modern engineering comprises many subfields which include designing and improving infrastructure, machinery, vehicles, electronics, Materials engineering, materials, and energy systems. The Academic discipline, discipline of engineering encompasses a broad range of more Academic specialization, specialized fields of engineering, each with a more specific emphasis for applications of applied mathematics, mathematics and applied science, science. See glossary of engineering. The word '':wikt:engineering, engineering'' is derived from the Latin . Definition The American Engineers' Council for Professional Development (the predecessor of the Accreditation Board for Engineering and Technology aka ABET) has defined "engineering" as: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Network
A clock network or clock system is a set of synchronized clocks designed to always show exactly the same time by communicating with each other. Clock networks usually consist of a central master clock kept in sync with an official time source, and one or more slave clocks which receive and display the time from the master. Synchronization sources The master clock in a clock network can receive accurate time in a number of ways: through the United States GPS satellite constellation, a Network Time Protocol server, the CDMA cellular phone network, a modem connection to a time source, or by listening to radio transmissions from WWV or WWVH, or a special signal from an upstream broadcast network. Some master clocks don't determine the time automatically. Instead, they rely on an operator to manually set them. Clock networks in critical applications often include a backup source to receive the time, or provisions to allow the master clock to maintain the time even if it lose ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Image
A disk image is a snapshot of a storage device's content typically stored in a file on another storage device. Traditionally, a disk image was relatively large because it was a bit-by-bit copy of every storage location of a device (i.e. every sector of a hard disk drive), but it is now common to only store allocated data to reduce storage space. Compression and deduplication are commonly used to further reduce the size of image files. Disk imaging is performed for a variety of purposes including digital forensics, cloud computing, system administration, backup, and emulation for digital preservation strategy. Despite the benefits, storage costs can be high, management can be difficult and imaging can be time consuming. Disk images can be made in a variety of formats depending on the purpose. Virtual disk images (such as VHD and VMDK) are intended to be used for cloud computing, ISO images are intended to emulate optical media, such as a CD-ROM. Raw disk images are use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Source Code Management
Version control (also known as revision control, source control, and source code management) is the software engineering practice of controlling, organizing, and tracking different versions in history of computer files; primarily source code text files, but generally any type of file. Version control is a component of software configuration management. A ''version control system'' is a software tool that automates version control. Alternatively, version control is embedded as a feature of some systems such as word processors, spreadsheets, collaborative web docs, and content management systems, e.g., Wikipedia's page history. Version control includes viewing old versions and enables reverting a file to a previous version. Overview As teams develop software, it is common to deploy multiple versions of the same software, and for different developers to work on one or more different versions simultaneously. Bugs or features of the software are often only present in ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACID
An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the proton donors, or Brønsted–Lowry acid–base theory, Brønsted–Lowry acids. In the special case of aqueous solutions, proton donors form the hydronium ion H3O+ and are known as Acid–base reaction#Arrhenius theory, Arrhenius acids. Johannes Nicolaus Brønsted, Brønsted and Martin Lowry, Lowry generalized the Arrhenius theory to include non-aqueous solvents. A Brønsted–Lowry or Arrhenius acid usually contains a hydrogen atom bonded to a chemical structure that is still energetically favorable after loss of H+. Aqueous Arrhenius acids have characteristic properties that provide a practical description of an acid. Acids form aqueous solutions with a sour taste, can turn blue litmus red, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multi-master Replication
Multi-master replication is a method of database replication which allows data to be stored by a group of computers, and updated by any member of the group. All members are responsive to client data queries. The multi-master replication system is responsible for propagating the data modifications made by each member to the rest of the group and resolving any conflicts that might arise between concurrent changes made by different members. Multi-master replication can be contrasted with primary-replica replication, in which a single member of the group is designated as the "master" for a given piece of data and is the only node allowed to modify that data item. Other members wishing to modify the data item must first contact the master node. Allowing only a single master makes it easier to achieve consistency among the members of the group, but is less flexible than multi-master replication. Multi-master replication can also be contrasted with High-availability cluster, failover ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Log
In computing, logging is the act of keeping a log of events that occur in a computer system, such as problems, errors or broad information on current operations. These events may occur in the operating system or in other software. A message or ''log entry'' is recorded for each such event. These log messages can then be used to monitor and understand the operation of the system, to debug problems, or during an audit. Logging is particularly important in multi-user software, to have a central overview of the operation of the system. In the simplest case, messages are written to a file, called a ''log file''. Alternatively, the messages may be written to a dedicated logging system or to a log management software, where it is stored in a database or on a different computer system. Specifically, a ''transaction log'' is a log of the communications between a system and the users of that system, or a data collection method that automatically captures the type, content, or time of tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database Replication
Replication in computing refers to maintaining multiple copies of data, processes, or resources to ensure consistency across redundant components. This fundamental technique spans databases, file systems, and distributed systems, serving to improve availability, fault-tolerance, accessibility, and performance. Through replication, systems can continue operating when components fail (failover), serve requests from geographically distributed locations, and balance load across multiple machines. The challenge lies in maintaining consistency between replicas while managing the fundamental tradeoffs between data consistency, system availability, and network partition tolerance – constraints known as the CAP theorem. Terminology Replication in computing can refer to: * ''Data replication'', where the same data is stored on multiple storage devices * ''Computation replication'', where the same computing task is executed many times. Computational tasks may be: ** ''Replicated in sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
