Study of Server Clustering Technology By Thao Pham and James Horton For CS526, Dr. Chow

Importance of Server Clustering Provide better service for end users –Better throughput –Faster turnaround time –Higher availability –Better reliability Provide dynamic scalability for businesses based on growing customer base

What is a Cluster? "a parallel or distributed system that consists of a collection of interconnected whole computers that is utilized as a single, unified computing resource.“ – G. Pfister One or more computers connected together to provide services from the “middle teir”. The number of computers and what services they provide should be transparent to the end user.

independent cluster methods the member servers are not aware of the other members redundancy is achieved by a third service (can be SPOF) weakness of availability : administrators to manually tell the cluster what to do

Centralized The Name servers keep track of which servers are up. same weakness as the independent, name servers can be SPOF. Servers need to know about additional name servers require server,can prolong the recovery time of the cluster.

global sharing cluster members know about one another. The information is presented globally in the cluster and locally in each machine. instant processing. takes longer to form due to initial traffic takes one single network call for a remote lookup.

HP TruCluster Server

TruCluster Componets Cluster file System (CFS) Device request dispatcher (DRD) Connection Manager Quorum Disk (optional) Cluster Alias Cluster Application Availability (CAA)

Cluster file System (CFS) Shared by all members, including a single /root file system /usr and /var Each member has it own boot partition

Quorum Disk Used for greater availability. has a vote of if present. when any node goes down, the cluster still maintains enough votes to stay active.

Device request dispatcher (DRD) controller of all I/O to physical devices and makes disks available to all cluster members.

Cluster Alias It is an IP address that makes some or all of the systems in a cluster look like a single system to TCP and User UDP applications

Connection Manager Forms a cluster, adds members to a cluster, and removes members from a cluster Tracks which members in a cluster are active Maintains a cluster membership list that is consistent on all cluster members Provides timely notification of membership changes using Event Manager (EVM) eventsEvent Manager Detects and handles possible cluster partitions

Cluster Application Availability (CAA) provides high availability for applications monitor applications, and the state of resources. Load balancing (automatically or manually) resources, resource profiles and action scriptsresourcesresource profilesaction scripts

Conclusion We learned quite a bit about a few different implementations of server clustering technologies. The surprising thing is not how different they are in their implementation, but how similar they are in their architecture. Ease of use award goes to Windows Server2003, but when things go wrong, it appears that TruCluster is better at reporting and deciphering the problem.