What is Session Cluster? 
Session Cluster is a high availability ASP.NET Session State Management Solution
Session Cluster provides a clustered Session State in .NET by performing cache synchronization across your web farm.
Each server in the web farm acts as a session store. If any one server fails the others will have its session data. There is no single point of failure and no dependency on SQL server.
no single point of failure
no reliance on slow database session management
no need to install a SQL server cluster to guarantee no single point of failure
extremely fast memory caching
Session Cluster is ideal for sites where SQL Server is not the main DBMS as MsSQL server is not required to achieve session clustering.
Requirements:
Installation is simple. You only have to change two entries in your global ‘web.config’ file. Once one machine is configured you use disk imaging software to copy your installation across the web farm.
Platform:
.Net 1.1 &.Net 2.0/3.5 (32/64bit)
Current ASP.NET Solutions:
| In Process |
Session data is kept in the server memory. This is very fast but the session data is not available to other servers in the farm. Session data will also be lost if the server reboots or the ASP.NET worker process recycles. |
| Microsoft StateServer |
Session is serialized and stored in memory in a separate process (aspnet_state.exe). The state server can run on another machine. However this creates a single point of failure as the stateserver cannot share the data with another state server. In addition a single server is taking all of the load. |
| SQLServer |
Session is serialized and stored in SQL server. This approach means you have to use Microsoft SQL Server in a clustered configuration to achieve high availability/failover. In addition you have a performance hit of up to 25% over the InProcess option. |
