OS

Introduction of Deadlock in Operating System A process in operating systems uses different resources and uses resources in following way. 1) Requests a resource 2) Use the resource 2) Releases the resource Deadlock  is a situation where a set of processes are blocked because each process is holding a resource and waiting for another resource acquired by some other process. Consider an example when two trains are coming toward each other on same track and there is only one track, none of the trains can move once they are in front of each other. Similar situation occurs in operating systems when there are two or more processes hold some resources and wait for resources held by other(s). For example, in the below diagram, Process 1 is holding Resource 1 and waiting for resource 2 which is acquired by process 2, and process 2 is waiting for resource 1. Deadlock can arise if following four conditions hold simultaneously (Necessary Conditions) Mutual Exclusion:  One or ...

Mutual exclusion in distributed system Mutual exclusion  is a concurrency control property which is introduced to prevent race conditions. It is the requirement that a process can not enter its critical section while another concurrent process is currently present or executing in its critical section i.e only one process is allowed to execute the critical section at any given instance of time. Mutual exclusion in single computer system Vs. distributed system: In single computer system, memory and other resources are shared between different processes. The status of shared resources and the status of users is easily available in the shared memory so  mutual exclusion problem can be easily solved. In Distributed systems, we neither have shared memory nor a common physical clock and there for we can not solve mutual exclusion problem using shared variables. To eliminate the mutual exclusion problem in distributed system approach based on message passing is used...

Event Ordering In a centralized system, we can always determine the order in which two events occurred, since the system has a single common memory and clock. Many applications may require us to determine order. For example, in a resource-allocation scheme, we specify that a resource can be used only  after  the resource has been granted. A distributed system, however, has no common memory and no common clock. Therefore, it is sometimes impossible to say which of two events occurred first. ... vent Ordering  In a centralized system, we can always determine the order in which two events occurred, since the system has a single common memory and clock. Many applications may require us to determine order. For example, in a resourceallocation scheme, we specify that a resource can be used only after the resource has been granted. A distributed system, however, has no common memory and no common clock. Therefore, it is sometimes impossible to say which of two even...

A distributed system contains multiple nodes that are physically separate but linked together using the network. All the nodes in this system communicate with each other and handle processes in tandem. Each of these nodes contains a small part of the distributed operating system software. A diagram to better explain the distributed system is − Types of Distributed Systems The nodes in the distributed systems can be arranged in the form of client/server systems or peer to peer systems. Details about these are as follows − Client/Server Systems In client server systems, the client requests a resource and the server provides that resource. A server may serve multiple clients at the same time while a client is in contact with only one server. Both the client and server usually communicate via a computer network and so they are a part of distributed systems. Peer to Peer Systems The peer to peer systems contains nodes that are equal participants in data sharing. All the ta...

High availability is a desirable feature of a good  distributed file system  and  file replication  is the primary mechanism for improving  file  availability. A  replicated file  is a  file  that has multiple copies, with each  file  on a separate  file  server. ... A cached copy is contingent upon a replica.

The key  difference between stateful and stateless  applications is that  stateless  applications don't “store” data whereas  stateful  applications require backing storage. ... Any associated storage is typically ephemeral. If the container restarts for instance, anything stored is lost. Difference between Stateless and Stateful Protocol Network Protocols  for web browser and servers are categorized into two types: Stateless Protocol, and Stateful protocol. These two protocols are differentiated on the basis of the requirement of server or server-side software to save status or session information. 1. Stateless Protocol: Stateless Protocols are the type of network protocols in which Client send request to the server and server response back according to current state. It does not require the server to retain session information or a status about each communicating partner for multiple request. HTTP (Hypertext Transfer Protocol) , ...

Search Results Featured snippet from the web Location  transparency  in commands used to perform a task is independent both of the locations of the data, and of the  system  on which an  operation  is carried out.  Naming transparency  means that a unique name is provided for each object in the database.

Definition - What does  Distributed File System (DFS)  mean? A distributed file system (DFS) is a file system with data stored on a server. The data is accessed and processed as if it was stored on the local client machine. The DFS makes it convenient to share information and files among users on a network in a controlled and authorized way. The server allows the client users to share files and store data just like they are storing the information locally. However, the servers have full control over the data and give access control to the clients. Techopedia explains  Distributed File System (DFS) There has been exceptional growth in network-based computing recently and client/server-based applications have brought revolutions in this area. Sharing storage resources and information on the network is one of the key elements in both local area networks (LANs) and wide area networks (WANs). Different technologies have been developed to bring convenien...

Network Topology  refers to layout of a network. How different nodes in a network are connected to each other and how they communicate is determined by the network's topology. BUS Topology Bus topology is a network type in which every computer and network device is connected to single cable. When it has exactly two endpoints, then it is called  Linear Bus topology . Features of Bus Topology 1.      It transmits data only in one direction. 2.      Every device is connected to a single cable Advantages of Bus Topology 1.      It is cost effective. 2.      Cable required is least compared to other network topology. 3.      Used in small networks. 4.      It is easy to understand. 5.      Easy to expand joining two cables together. Disadvantages of Bus Topology 1.      Cables fails then whole ...