In a Citrix XenServer, a physical block device is a connector object that represents the interface between a physical host and an attached storage repository (SR). A physical block device is responsible for storing the device configuration fields that are used to connect to, and interact with, a given storage target. It also manages the run-time attachment of a given storage repository to a given host.
Learn more about PBDs and their parameters and commands by reading the XenServer Administrator's Guide.
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