only presentation

1. Welcome to our Presentation

2. Presented to :
Dhiman Goshwami
Lecturer
Daffodil International University
PRESENTED BY:
 KAWSAR HASAN ( 161-15-6951)
 MAHMUDUL HAQUE (161-15-6950)

3. Topics: Fault tolerance

4. Content:
 Fault Tolerance
 Requirements
 Fault Tolerance Vs. High Availability
 Advantages & Disadvantages
 Example

5. What is fault tolerance?
Fault-tolerance Or Graceful Degradation Is The Property That Enables A System (Often Computer-
based) To Continue Operating Properly In The Event Of The Failure Of (Or One Or More Faults
Within) Some Of Its Components.

7. Requirements
 NO SINGLE POINT OF FAILURE
 FAULT ISOLATION TO THE FAILING COMPONENT
 FAULT CONTAINMENT TO PREVENT PROPAGATION OF THE FAILURE
 AVAILABILITY OF REVERSION MODES

8. FAULT TOLERANCE VS. HIGH
AVAILABILITY
High Availability Refers To A System’s Ability To Avoid Loss Of Service By Minimizing Downtime. It’s
Expressed In Terms Of A System’s Uptime, As A Percentage Of Total Running Time.
Downtime – A Highly Available System Has A Minimal Allowed Level Of Service Interruption. For Example, A
System With “Five Nines” Availability Is Down For Approximately 5 Minutes Per Year.
Scope – High Availability Builds On A Shared Set Of Resources That Are Used Jointly To Manage Failures And
Minimize Downtime. Fault Tolerance Relies On Power Supply Backups
Cost – A Fault Tolerant System Can Be Costly, As It Requires The Continuous Operation And Maintenance Of
Additional, Redundant Components. High Availability Typically Comes As Part Of An Overall Package Through
A Service Provider

10. Disadvantages :
 Interference With Fault Detection In The Same Component.
 Interference With Fault Detection In Another Component
 Reduction Of Priority Of Fault Correction.
 Test Difficulty.
 Cost

11. Example :
LOAD BALANCING AND FAILOVER: FAULT TOLERANCE FOR
WEB APPLICATIONS

12. Examplesof FaultTolerantSystems
AIRBUSA320/A330/A340 FlightControl Computer
The primary module sends its commands to the actuators, withthe secondary module remaining in standby.
When the primary module fails,it is taken offline and the secondary module takes over the command
function. Inaddition, asecondpair of modules.

13. Thank You