Ch16 - 16.04 - Understanidng High Availability

Question 1

High Availability

Answer 1

High availability is ensuring that clients can always gain access to the services that they need, whether it be an e-mail server, database server, or a WAN link. To have high availability, you must first identify all of your single points of failure and then create redundancy in those areas. The following are some key areas where single points of failure are found:

1. Servers
2. Hard drives
3. Network equipment such as routers and switches
4. WAN/Internet links
5. Power

Question 2

Failover Clustering

Answer 2

The first technology that is commonly used to ensure high availability is failover clustering. With failover clustering, you install multiple servers (known as nodes) that run the same software. The two or more nodes act as a team, with one node acting as the active node and the other nodes acting as passive nodes. When the active node fails, a passive node comes online to
take over the workload.

Question 3

Network Load Balancing

Answer 3

Network load balancing is an important technology that is designed to improve the performance of an application such as a web site. For example, if you find that your web site has grown in popularity and is being bogged down with requests, you can install multiple servers into a load-balanced array. The clients then connect to an IP address assigned to the load-balanced array which then redirects the clients to one of the available servers in the array