Deployment Options (Velocity)

Security Considerations

The "Velocity" distributed cache system is designed to be operated in the corporate datacenter within the perimeter of the corporate firewall. The servers described in this topic are the server hosting the cache configuration storage location, the cache servers, the cache-enabled application servers, the development servers, and the primary data source server. All servers should be co-located on the same corporate domain.

Because cached data and the TCP/IP communications between the cache servers is not encrypted, the distributed cache system is vulnerable to malicious "sniffing" and "replay" attacks.

Note

The "Velocity" cache client is meant to reside in the application tier of your application ecosystem. End users inside or outside your corporate domain should not have direct network access to the cache servers.

When decommissioning a cache server, the "Velocity" installation program may not remove all firewall port exceptions. After "Velocity" has been uninstalled, we recommend that you reapply the corporate standard firewall configuration.

Deployment Scenarios

To simplify the discussion of deployment options, this topic will focus on three distinct examples:

• Developer deployment: A single-computer deployment used by to develop cache-enabled applications.

• Mid-sized deployment: A multi-computer installation that does not use SQL Server, with lead hosts performing the cluster management role.

• Enterprise deployment: A multi-computer installation that uses SQL Server for storing cluster configuration settings and performing the cluster management role.

Cluster Management and Lead Host Designations

There are two main configuration settings that determine how the cluster functions with respect to cluster management:

leadHostManagement : This cluster-level setting determines what will perform the cluster management role. When true, lead hosts perform the cluster management role. If you have chosen to store your cluster configuration settings in a shared network folder, true is the only valid value for this setting. False indicates that SQL Server will perform the cluster management role. If you have chosen to store your cluster configuration settings in SQL Server, this setting will default to false. When using SQL Server to store cluster configuration settings, you can set this setting to true and let lead hosts perform the cluster management role.

quorumHost : This cache host-level setting determines which cache hosts will be lead hosts when lead hosts perform the cluster management role. Even if SQL Server is going to perform the cluster management role, the installation program designates lead hosts, in case you later change the LeadHostManagement setting.

For more information about changing these settings, see How to: Set the Cluster Management Role and Lead Host Designations (Velocity).

Note 
The "quorum" reference is a term that was used in a previous community technology preview (CTP) of "Velocity" to refer to a lead host. The name of this setting may change in the future.