Local clustering the next level is a application

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Local clustering: The next level is a application clustering solution, such as Veritas Cluster Server, for application and server availability. Remote replication: After implementing local availability, you can further ensure data availability in the event of a site failure by replicating data to a remote site. Replication can be application-, host-, or array-based. Remote clustering: Implementing remote clustering ensures that the applications and data can be started at a remote site.Veritas Cluster Server supports remote clustering with automatic site failover capability.
1–4 Symantec Cluster Server 6.x for UNIX: Administration Fundamentals Copyright © 2014 Symantec Corporation. All rights reserved. Costs of downtime A Gartner study shows that large companies experienced a loss of between $954,000 and $1,647,000 (USD) per month for nine hours of unplanned downtime. In addition to the monetary loss, downtime also results in loss of business opportunities and reputation. Planned downtime is almost as costly as unplanned. Planned downtime can be significantly reduced by migrating a service to another server while maintenance is performed. Given the magnitude of the cost of downtime, the case for implementing a high availability solution is clear.
Lesson 1 High Availability Concepts 1–5 Copyright © 2014 Symantec Corporation. All rights reserved. 1 Clustering concepts The term cluster refers to multiple independent systems connected into a management framework. Types of clusters A variety of clustering solutions are available for various computing purposes. HA clusters: Provide resource monitoring and automatic startup and failover Parallel processing clusters: Break large computational programs into smaller tasks executed in parallel on multiple systems Load balancing clusters: Monitor system load and distribute applications automatically among systems according to specified criteria High performance computing clusters: Use a collection of computing resources to enhance application performance Fault-tolerant clusters: Provide uninterrupted application availability Fault tolerance guarantees 99.9999 percent availability, or approximately 30 seconds of downtime per year. Six 9s (99.9999 percent) availability is appealing, but the costs of this solution are well beyond the affordability of most companies. In contrast, high availability solutions can achieve five 9s (99.999 percent availability—less than five minutes of downtime per year) at a fraction of the cost. The focus of this course is Veritas Cluster Server, which is primarily used for high availability, although it also provides some support for parallel processing and load balancing.
1–6 Symantec Cluster Server 6.x for UNIX: Administration Fundamentals Copyright © 2014 Symantec Corporation. All rights reserved. Local cluster configurations Depending on your clustering solution, you may be able to implement a variety of configurations, enabling you to deploy the clustering solution to best suit your HA requirements and utilize existing hardware.

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