This is the outline, first of all we have the introduction, then the defenition. afterthatwewillsee the clusetrring
imagine that this happens to a large company such as Amazon which has 100 billion stored objects and 760 million visitor per daythe consequences will be catastrophic as the lack of productivity, loss of money, loss of integrity
In computers, clustering is the use of multiple computers, typically PCs or UNIX workstations, multiple storage devices, and redundant interconnections, to form what appears to users as a single highly available system. Cluster computing can be used for load balancing as well as for high availability. Advocates of clustering suggest that the approach can help an enterprise achieve 99.999 availability in some cases. One of the main ideas of cluster computing is that, to the outside world, the cluster appears to be a single system.
In broad terms, a cluster is a group of independent systems working together as a single system. A client interacts with a cluster as though it is a single server. Cluster configurations are used to address both availability and scalability:
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The most common size for an HA cluster is a two-node cluster, since that's the minimum required to provide redundancy, but many clusters consist of many more, sometimes dozens of nodes.
Attached to all nodes of the cluster. Each disk on the cluster storage is owned by only one node of the cluster at a time. The ownership of disks moves from one node to another during failover or when the administrator moves a group of resources to another node
A High Availability Cluster is the best way to setup a service which must behigh available because several failures may occur and the service will still beavailable. Upgrading servers is a lot less stressful if a High Availability Cluster isused because there is always another server which will take over the connectionto the service.
Problematic catastrophic Normally, if a server with a particular consequencesapplication crashes, the application will beunavailable until someone fixes the crashedserver. the lack of loss of money loss of integrityproductivity 2
Problematicsystem downtime costs : U.S. businesses $4.0billion per year1$140,000 loss in theretail industry$450,000 loss in thesecurities industry2 3
Solution • the solution to this problem is the use of High Availability, or HA, is the term associated with computer systems which exhibit almost no downtime4
Definition • computers, clustering is the use of In can help an enterprise achieve 99.999 multiple computers, instoragecases. availability some devices, and redundant interconnections, to form what appears to users • a the outside available system as tosingle highly world, the cluster appears to be a single system.6
Clustering Cluster address The teacher is solely responsible stewardship of EYP; When a system in the cluster fails, the cluster he can add,clustering technology, customers will be Using edit or delete it. He also has the softwareto incrementally add smaller, standardthe possibility responds by dispersing the work from able to attach to the EYP a document that failed system todetailremaining systems in the cluster. systems as the the EYP. explains in more needed to meet overall processing power requirements7
When should we use HA clustering ?HA clusters are often used :• Critical databases• File sharing on a network.• Business applications.• Customer services such as electronic commerce websites. 8
Understanding Common terms Noeds Failover HA clustering Cluster storage9
Understanding Common terms• HA clustering operate by having a computer system that is an active or inactive member of a cluster, used to provide service when system components fail. 10
Understanding Common terms• when we talk about high availability, we talk about : the process of taking a group of clustered resources offline on one node and bringing them online on another node. 11
Understanding Common termsEach diskAttached of disks moves the cluster.only to The ownership to all storage isfrom one node one on the cluster nodes of owned by another during failover or when a time node of the cluster at the administrator moves a group of resources to another node12
HA TWO-NODE CLUSTER PLATFORM Clients Public LAN Private LAN Cluster NODE1 NODE2 SAN SCSI Interfaces RAID Level 113
Disadvantage of HA• The disavantage appears when we talk about open-source High Availability Cluster:• poor documentation and the lack of support in the maintenance and customization• can only be done by someone who has experience with Linux/Unix. 14