It's amazing to see how fast the usage of a web application can outpace initial expectations. Growth is good for business but creates some real challenges when it comes to trying to keep everything up and running speedily along.
When an application is being designed, estimates are made for the expected maximum load of web traffic and the number of concurrent requests that the databases will need to handle. Often these estimates turn out to be too conservative (and sometimes even way off base), so software architects need to plan for much greater application load to avoid major redesigns in the future. These plans usually need to include a database scale-out strategy.
Scaling web applications and databases can be quite complex depending on the requirements but the good news is that for the majority of web applications, it can be done with little impact on a project's timeline or budget provided it's taken into account at the beginning of the design cycle and not as an afterthought.
When an application is being designed, estimates are made for the expected maximum load of web traffic and the number of concurrent requests that the databases will need to handle. Often these estimates turn out to be too conservative (and sometimes even way off base), so software architects need to plan for much greater application load to avoid major redesigns in the future. These plans usually need to include a database scale-out strategy.
Scaling web applications and databases can be quite complex depending on the requirements but the good news is that for the majority of web applications, it can be done with little impact on a project's timeline or budget provided it's taken into account at the beginning of the design cycle and not as an afterthought.
Read more under http://www.novologies.com/post/2009/03/25/Database-Scale-Out-Strategies-for-Web-Apps.aspx