Midterm Distributed questions homework

.What is meant by a scalable system?

A scalable system means it can still be just as effective as the changes happen and workload

increases. Like if for more servers are added. They need to be easily added to the current system making

it scalable

.What is the role of middleware in a distributed system?

Middleware’s role a software layer that extends over multiple machines. It offers each machine

the same interface. It lets access to the programming interface even among different OS

In the Chord system, how does a node join the system? How does a node leave the system?

A node joins by contacting the boot node. Then the boot node assigns another node a unique

identifying code. Then updaes it to reflect the added node’s presences

What is the basic architecture of a NFS system for UNIX?

the basic architecture is a file server that stores the files and can share them with many clients.

The clients can then mount these files to their own file systems, allowing the clients to access the files on

the server as if it were local ones.

In the OSI model, what are the seven layers and their functionalit

Phyiscal Layer- Deals with the physical connections of devices. Think of the wires and stuff.

Data link layer – The layer of two nodes in a network. Handles error detection

Network Layer – Routing the data packets to other networks

Trasport Layer – End to end communication that ensures the data stays right

Session Layer – maintains and terminations the communication sessions

Presentation Layer – Controls the encryption and that data is in correct understandable formats

Application layer- Top most and it is the layer that user sees

What are the advantages of disadvantages of user-level threads? What are the

advantages of disadvantages of kernel-level threads

User level threads are lightweight and they are managed by the application itself. They can be used across different operating systems too. It’s issues is that it’s not as compatible with multi core processors and a use level thread can potentially block all threads in the same process

Kernal level threads can run on multiple cpu cores and can handle thread failures rather well. But it struggles in creating and managing kernal threads involving the system’s call. Which can be a

lot slower.

What is the advantage of using virtualization when designing a system?

Virtualization is good about creating virtual machines. These machines will have it’s own resources and kep it from affecting another VM on the same system. It is perfect for testing and monitoring. These are perfect creating a isolating effect keeping viruses in it and escaping to the

main system