Load Balancing Methods - TMOS 201 Flashcards
Name two static load balancing methods.
Round robin and ratio
Name six dynamic load balancing methods.
1) least connections
2) fastest
3) weighted least connections
4) least session
5) observed
6) predictive
What are two load balancing failure mechanisms?
1) priority group activation
2) failback host
What is ratio load balancing?
Connection distributed in weighted round robin pattern define by ratio configuration - applied to member or node.
What is least connections (member) load balancing?
The system passes a new connection to the node that has the least number of current connections in the pool.
What is least connections (node) load balancing?
The system passes a new connection to the node that has the least number of current connections out of all pools of which a node is a member.
What is fastest (node) load balancing?
The system passes a new connection based on the fastest response of all pools of which a server is a member. This method might be particularly useful in environments where nodes are distributed across different logical networks.
What is fastest (application) load balancing?
Passes a new connection based on the fastest response of all currently active nodes in a pool. This method might be particularly useful in environments where nodes are distributed across different logical networks.
What is weighted least connections (node) load balancing?
The system uses the value you specify in the node’s Connection Limit and the number of current connections to a node to establish a proportional algorithm. This algorithm requires all nodes used by pool members to have a non-zero connection limit specified.
What is weighted least connections (member) load balancing?
The system uses the value you specify in Connection Limit to establish a proportional algorithm for each pool member. The system bases the load balancing decision on that proportion and the number of current connections to that pool member. For example, member_a has 20 connections and its connection limit is 100, so it is at 20 percent of capacity. Similarly, member_b has 20 connections and its connection limit is 200, so it is at 10 percent of capacity. In this case, the system select selects member_b. This algorithm requires all pool members to have a non-zero connection limit specified.
What is least sessions load balancing?
The system passes a new connection to the node that currently has the least number of persistent sessions.
What is observed (node) load balancing?
The system ranks nodes based on the number of connections. Nodes that have a better balance of fewest connections receive a greater proportion of the connections.
This method tracks the number of Layer 4 connections to each node over time and creates a ratio for load balancing.
What is observed (member) load balancing?
The system ranks nodes based on the number of connections. Nodes that have a better balance of fewest connections receive a greater proportion of the connections. This only applies to the member of the pool.
What is predictive load balancing?
Uses the ranking method used by the Observed (member) methods, except that the system analyzes the trend of the ranking over time, determining whether a node’s performance is improving or declining.
What is fallback host?
A fallback host redirect a user to a different page/URI or a different server (maintenance server hosting a site is down message).
