An affinity group is a group of IBM® Content Search Services index servers and index areas. The servers in a group access only those index areas in the same group. The servers that are not in a group access only those index areas that are not in a group.
In the absence of affinity groups, the Content Platform Engine assignment of an index server to an index is subject to one restriction: the index server must belong to the same site as the relevant index area. Content Platform Engine automatically assigns a different index server to a full-text index as necessary to balance server workloads. Create affinity groups if the attempt by Content Platform Engine to evenly balance the server workload across the entire site is not desired. In particular, dedicating index servers to particular index areas might be useful in the following cases:
Avoiding network traffic | Dedicating an index server to the index area on a local file system can eliminate network traffic and so make indexing faster and more efficient. |
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Limiting the demand on weak servers | The statistical averages that Content Platform Engine uses to measure indexing speeds might not accurately represent the true indexing speed of a server. Dedicating weak index servers to a limited number of index areas limits the demands on these servers. |
Setting indexing priorities for object stores | Indexing documents quickly for some object stores might be less important than for other object stores. Dedicating a limited number of index servers to those index areas for the object stores with the less urgent indexing requirements can reflect these priorities. |