Submitted by: Shailendra Kumar Sharma 06EYTCS049

Agenda Introduction The Linux Virtual Server framework General architecture Technology Overview Literature Development Working Principle Characteristics of LVS Conclusion References

What is Virtual Server ?? Virtual server is a highly scalable and highly available server. It is built on a cluster of real servers. The architecture of server cluster is fully transparent to end users. The Users interact with the cluster system.

The load balancers can dispatch requests to the different servers and make parallel services of the cluster to appear as a virtual service on a single IP address, and request dispatching can use IP load balancing technologies or application-level load balancing technologies.

Framework

General Architecture 3 tiers Load balancer Server cluster Shared storage

Technology Overview: Compute clustering (such as Beowulf) uses multiple machines to provide greater computing power for computationally intensive tasks. High-availability (HA) clustering uses multiple machines to add an extra level of reliability for a service or group of services. Load-balance clustering uses specialized routing techniques to dispatch traffic to a pool of servers.

Configurations: While Red Hat Enterprise Linux can be configured in a variety of different ways, the configurations can be broken into two major categories: High-availability clusters using Red Hat Cluster Manager. Load-balancing clusters using Linux Virtual Servers.

Literature Development IPVS NAT IP Masquerading Networking(TCP/IP) Implementation in Linux Kernel Scheduling

IP Virtual Server Implemented in the Linux kernel Three IP load balancing techniques Virtual Server via NAT Virtual Server via IP Tunneling Virtual Server via Direct Routing Eight scheduling algorithms

VS/NAT

Working Principle: There are service monitor daemons running on the load balancer to check server health periodically, the service monitor will consider the server is dead and remove it from the available server list at the load balancer. Thus no new requests will be sent to this dead server. When the service monitor detects the dead server has recovered to work, the service monitor will add the server back to the available server list.Use system tools to add new servers to increase the system throughput or remove servers for system maintenance.

Characteristics LVS extends Linux kernel to support three IP load balancing techniques Eight scheduling algorithms High scalability (up to 100 nodes) High availability Supporting most TCP and UDP services, no modifications to either clients or servers

Call to Action(Conclusion) Building scalable network services is complicated and expensive LVS is here to help make your life easier LVS is proven stable, and is being deployed by more and more sites.

References [1] www reference [2] Server Clusters: Build highly-scalable and highly- available network services at low cost”, November 2003, Linux Magazine [3] [4]