Guide to Technology


eg: UK or Brides UK or Classical Art or Buy Music or Spirituality

Business & Money

Technology

Women

Health

Education

Family

Travel

Cars

Entertainment

Load Balancing In Windows

View:

Load balancing, by definition, is the process of spreading the amount of work that is conducted by a computer system between a number of different computer systems to increase the speed that the work is completed in. There are several different methods in which load balancing can be accomplished by and the technique can use many different types of computer components, including both hardware and software applications. Load balancing is typically completed using a cluster of computer servers that may or may not be located in the same location.

There are many different companies that see the benefits of using and implement the procedure for their companies. Companies that conduct business transactions in large numbers using the internet are prime candidates to use load balancing to ensure that all of their clients and customers will be able to conduct their transactions quickly and accurately. Companies that need to network a great deal of computers for individual users also typically use load balancing to ensure that all computers will work properly and have the right amount of power to be able to perform the functions that they are intended to perform. It also ensures that the company will still be able to do business if one server becomes corrupted or goes down for an extended period of time.

There are several different methods that are widely used for load balancing. One of the most popular methods of load balancing is Global Server Load Balancing. This technique distributes the incoming tasks to a group of servers in a particular geographic location. This technique is widely used by companies that have a global presence and have a need to satisfy customers or employees in many different geographical locations. Using Global Server Load Balancing ensures that the work load is distributed throughout the entire server system in an easy to manage manner and ensures that all geographical locations are obtaining the correct information from the correct set of servers.

Another load balancing technique that is commonly used is called Persistence Load Balancing. This technique assigns each new client to a different server in a round robin type of allocation. This client is then assigned to this specific server for the future of their relationship with the business. This ensures that no one server is overloaded with a particular type of client, such as those in a certain geographical area or use a specific type of service and ensures that the clients are distributed evenly through out all of the servers that the business possesses. These server assignments are typically monitored by using the customers IP address as the customer's unique identification code.

Load Balancing In Windows

Oracle RAC systems provide two methods of failover to provide reliable access to data:

Connection failover.

If a connection failure occurs at connect time, the application can fail over the connection to another active node in the cluster. Connection failover ensures that an open route to your data is always available, even when server downtime occurs.

Transparent Application Failover (TAF).

If a communication link failure occurs after a connection is established, the connection fails over to another active node. Any disrupted transactions are rolled back, and session properties and server-side program variables are lost. In some cases, if the statement executing at the time of the failover is a Select statement, that statement may be automatically re-executed on the new connection with the cursor positioned on the row on which it was positioned prior to the failover.

The primary difference between connection failover and TAF is that the former method provides protection for connections at connect time and the latter method provides protection for connections that have already been established. Also, because the state of the transaction must be stored at all times, TAF requires more performance overhead than connection failover.

Connection Enabling connection failover allows a driver to connect to another node if a connection attempt on one node fails. When an application requests a connection to an Oracle database server through the driver, the driver does not connect to the database server directly. Instead, the driver sends a connection request to a listener process, which forwards the request to the appropriate Oracle database instance. In an Oracle RAC system, each active Oracle database instance in the RAC system registers with each listener configured for the Oracle RAC.

Transparent Application Failover (TAF)

With TAF, if a communication link failure occurs after a connection is established, the connection is moved to another active Oracle RAC node in the cluster without the application having to re-establish the connection.

Load Balancing

Oracle RAC systems provide two types of load balancing for automatic workload management:

Server load balancing distributes processing workload among Oracle RAC nodes.

Client load balancing distributes new connections among Oracle RAC nodes so that no one server is overwhelmed with connection requests. For example, when a connection fails over to another node because of hardware failure, client load balancing ensures that the redirected connection requests are distributed among the other nodes in the RAC.

The primary difference between these two methods is that the former method distributes processing and the latter method distributes connection attempts.

Server Load Balancing

With Oracle9i RAC systems, a listener service provides automatic load balancing across nodes. The query optimizer determines the optimal distribution of workload across the nodes in the RAC based on the number of processors and current load.

Oracle 10g also provides load-balancing options that allow the database administrator to configure rules for load balancing based on application requirements and Service Level Agreements (SLAs). For example, rules can be defined so that when Oracle 10g instances running critical services fail, the workload is automatically shifted to instances running less critical workloads. Or, rules can be defined so that Accounts Receivable services are given priority over Order Entry services.

The DataDirect Connect for ODBC Oracle drivers can transparently take advantage of server load balancing provided by an Oracle RAC without any changes to the application. If you do not want to use server load balancing, you can bypass it by connecting to the service name that identifies a particular RAC node.

Client Load Balancing

Client load balancing helps distribute new connections in your environment so that no one server is overwhelmed with connection requests. When client load balancing is enabled, connection attempts are made randomly among RAC nodes. You can enable connection failover for DataDirect Connect for ODBC drivers through a driver connection string using the Load Balancing connection string attribute.

Suppose you have the Oracle RAC environment shown in Figure 4 with multiple Oracle RAC nodes, A, B, C, and D. Without client load balancing enabled, connection attempts may be front-loaded, meaning that most connection attempts would try Node A first, then Node B, and so on until a connection attempt is successful. This creates a situation where Node A and Node B can become overloaded with connection requests.

With client load balancing enabled, the driver randomly selects the order of the connection attempts to nodes throughout the Oracle RAC system. For example, Node B may be tried first, followed by Nodes D, C, and A. Subsequent connection retry attempts will continue to use this order. Using a randomly determined order makes it less likely that any one node in the Oracle RAC system will be so overwhelmed with connection requests that it may start refusing connections.

For more details on Oracle RAC you can view on

Related Articles
Author
Most Popular

•	Application Server Load Balancing, by Highreplica Highreplica
•	Backup Files In Windows, by Roland Jefferson
•	Clustering And Load Balancing, by Highreplica Highreplica
•	Copy Files In Windows, by Elizabeth Boston
•	Differences In Windows 7, by John Kunkle

About Author

Both Know More About Load Balancing & Hitechwriter are contributors for EditorialToday. The above articles have been edited for relevancy and timeliness. All write-ups, reviews, tips and guides published by EditorialToday.com and its partners or affiliates are for informational purposes only. They should not be used for any legal or any other type of advice. We do not endorse any author, contributor, writer or article posted by our team.

Know More About Load Balancing has sinced written about articles on various topics from Information Technology. Fusepoint is a full suite of managed IT services including: . Fusepoint sees the benefits of using. Know More About Load Balancing's top article generates over 880 views. to your Favourites.

Hitechwriter has sinced written about articles on various topics from Software, Information Technology and Software. is a blog site of Sagar Patil, an independent oracle consultant with a great understanding of how the Oracle database engine & Oracle App. Hitechwriter's top article generates over 6600 views. to your Favourites.

Clubs The Pros Use
You can also join there forum and chat to traders around the world, or visit there broker section and see who the expert recommend. This site is a must for anyone serious about trading