Description
High availability clusters (HAC) improve application availability by failing them over or switching them over in a group of systems—as opposed to High Performance Clusters, which improve application performance by running them on multiple systems simultaneously.
Most Veritas Cluster Server implementations attempt to build availability into a cluster, eliminating single points of failure by making use of redundant components like multiple network cards, storage area networks in addition to the use of VCS.
Similar products include Fujitsu PRIMECLUSTER, IBM PowerHA System Mirror, HP Serviceguard, IBM Tivoli System Automation for Multiplatforms (SA MP), Linux-HA, Microsoft Cluster Server (MSCS), NEC ExpressCluster, Red Hat Cluster Suite, SteelEye LifeKeeper and Sun Cluster. VCS is one of the few products in the industry that provides both high availability and disaster recovery across all major operating systems while supporting 40+ major application / replication technologies out of the box.
VCS is mostly a user-level clustering software; most VCS processes are normal system processes on the systems it operates on, and have no special access to the Operating System or kernel functions in the host systems. However, the interconnect (heartbeat) technology used with VCS is a proprietary Layer 2 ethernet-based protocol that is run in the kernel space using kernel modules. The group membership protocol that runs on top of the interconnect heartbeat protocol is also implemented in the kernel. In case of a split brain, the 'fencing' module does the work of arbitration and data protection. Fencing too is implemented as a kernel module.
Veritas Cluster Server for Windows is available as a standalone product. It is also sold bundled with Storage Foundation as Storage Foundation HA for Windows; Veritas Cluster Server for AIX, HP-UX, Linux, and Solaris is supplied as a standalone product.
The Veritas Cluster Server product includes VCS Management Console, a multi-cluster management software that automates disaster recovery across data centers.
Read more about this topic: Veritas Cluster Server
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