1. In simple words we can say that high availability refers to the availability of resources in a computer system.
2. In terms of cloud computing it refers to the availability of cloud services.
3. High availability is the heart of the cloud.
4. It provides the idea of anywhere, anytime access to service of cloud environment.
5. Availability is also related to reliability.
6. Availability is a technology issue as well as business issue.
7. High Availability can be simply defined by the simple equation:
Where , MTBF – mean time between failures, MTTR- means time to repair and HA- high availability.
8. There is two way improve the availability:-
- Increase MTBF to very large values.
- Reduce MTTR to very low values.
1. Disaster recovery (DR) is the process, policies and procedures that are related to preparing for recovery or continuation of technology infrastructure which are an organization after a natural or human-induced disaster.
2. A disaster recovery is the process by which an organization can recover and access their software, data, and hardware.
3. It is necessary for faster disasters recovery to have an infrastructure supporting high availability.
4. The failure of disaster recovery plan mainly due to lack of high availability preparation, planning and maintenance to occurrence of the disaster.
Strategies of Disaster Recovery:
1. RTO (Recovery Time Objective):
RTO is the period of time within which system, application, or functions must be discovered after an outage. RTOs are often used as the basis for the development of recovery strategies and as determinant as to whether or not to implement the recovery strategies during a disaster situation.
2. RPO (Recovery point objective):
RPO is the point to time to which systems and data must be recovered after an outage. RPOs are often used as the basis for the development of backup strategies, and as a determinant of the amount of data that may need to be recreated after the systems or function have been recovered.