Clustering - Eric Vanderburg
Download as PPT, PDF0 likes202 views
Clustering involves combining computers to create a logical computer that provides increased redundancy. A cluster uses nodes, resources, resource groups, and storage area networks. There are different types of cluster models including local quorum, single quorum device, and majority node set clusters. Storage is accessed through zoning and LUN masking to control traffic flow and provide security. Replication can be done at the block, file system, or application level between sites and can be synchronous, where an operation is complete only after replication, or asynchronous, where an operation can be considered complete before replication.
Clustering - Eric Vanderburg
- 2. CLUSTERING • Combining computers to create one logical computer • Provides increased redundancy
- 3. TERMS • Node (cluster host) - A computer that is a member of a server cluster. • Resource - entity that can be managed by a cluster and moved between nodes. • Resource Group - A collection of resources that can be started or stopped. • Failover - the process of taking resources offline on one node and moving them to another. • Failback - returning resources back to their original node once it has recovered. • Quorum - the disk that holds the configuration data and all the changes that have been made to the cluster database. • HBA (Host Bus Adapter) - interface card that connects a cluster node to a SAN. • Split brain - some nodes in the cluster lose contact with the quorum and one another so each thinks that they are the only one in the cluster. This eventually leads to data corruption.
- 4. INSTANCES • Single Instance application - One application is running on the server at a time • Multiple instance application - multiple instances of the same code or different pieces of code running for the same service are running on a cluster. • Cloned applications - uses a relatively static dataset. • Partitioned application - dataset is frequently updated so the dataset is divided among partitions.
- 5. STORAGE • Clusters use SANs for storage • Cluster network should be connected directly to the SAN and the network between them should be isolated from the rest of the network. • Parallel SCSI • Fiber Channel • If there are more than 2 nodes,m FC-SW (Switched Fiber Channel Fabric) must be used.
- 6. ACCESS TO THE SAN • Zoning - creates views called clouds that control access and control traffic flow between the SAN. • LUN masking - access control is provided at the controller and port level. Policies are defined for specific devices. Provides more granular security than zoning.
- 7. CLUSTER MODELS • Local Quorum cluster - used for testing and has only one node. • Single Quorum device cluster - cluster configuration data is stored on a single device connected to all nodes in the cluster. At least one node must be functional for the cluster as a whole to function. • Majority node set cluster - each node contains its own copy of the cluster configuration data. A majority of the nodes in the cluster must function for the cluster as a while to function.
- 8. MULTISITE CLUSTER REPLICATION • Block level replication - storage devices are mirrored over a private network between sites. • File system level replication • Application level replication
- 9. SYNCHRONOUS & ASYNCHRONOUS • Synchronous replication - an operation is not complete until it has been replicated to partner sites • Asynchronous replication - an operation can be considered complete before it has been replicated to partners.
- 10. SYNCHRONOUS & ASYNCHRONOUS • Synchronous replication - an operation is not complete until it has been replicated to partner sites • Asynchronous replication - an operation can be considered complete before it has been replicated to partners.