Scaling Internet services by LinuxDirector

LinuxDirector is a software tool that directs network connections to multiple servers that share their workload, which can be used to build highly scalable and highly available services. LinuxDirector extends the TCP/IP stack of the Linux kernel to support three IP load balancing techniques, which can make parallel services of different kinds of server clusters to appear as a service on a single IP address. Four scheduling algorithms have been implemented to assign connections to different servers, and a simple distributed lock manager is provided for applications on different servers to access shared data consistently. Scalability is achieved by transparently adding or removing a node in the cluster and high availability is provided by detecting node or daemon failures and reconfiguring the system appropriately. This paper describes the design and implementation of LinuxDirector and presents several of its features including scalability, high availability, connection affinity and icmp handling.