The vCenter server database holds the configuration of your clusters, including DRS, HA, DPM, etc. About vMotion, it depends, if you're using standard vSwitch, the vMotion network settings are managed and stored at host level, if using distributed vSwitch, information are managed and stored at vCenter level and the host caches this configuration locally.
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Richardson Porto
Senior Infrastructure Specialist
LinkedIn: http://linkedin.com/in/richardsonporto