Rackable Systems OmniStor 4900F Series, Руководство пользователя

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Chapter 2 - Topologies and Operating Modes
Minimizing Downtime for Maximum Data Availability
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from one node to two nodes. Going from one node to a four node cluster generally yields a
2.5x or 3x performance boost. However, the cluster performance is application dependent.
For example, READ operations may yield a 1.8x performance increase going from one to
two nodes, but in a WRITE intensive application, you may only see a 1.4-1.6x
improvement.
Although clusters seem to be relatively simple, they involve complex technology that can be
implemented in a variety of ways. The number of nodes supported and type of
interconnection used, and a number of other features differentiate cluster implementations.
One area of implementation is the manner in which distributed lock manager is
implemented. Some perform this at the user level and others in the kernel, with the latter
enhancing performance.
In addition to the differences of features you should consider the following:
Does the cluster:
• have the ability to hot load new nodes without bringing down the whole
cluster?
• provide automatic or manual failover?
• load balance?
• use a journalized file system?
• provide a fast cluster failover?
• allow for the nodes to be geographically located?