All access to data and metadata on a File Server machine is managed by the File Exporter. Clients contact the File Exporter when they wish to access data. The Cache Manager is the client of the File Exporter most visible to the user, as well as the one most frequently discussed in this guide, but other clients do exist. For example, the fts program can become a client of the File Exporter when a fileset is moved from one aggregate or machine to another, and the Replication Server is a frequent client of the File Exporter as it manages replicas of read/write filesets.
The File Exporter uses tokens to manage the distribution of data and metadata to clients. A client that wants to access or change data must first request and obtain the proper tokens for the data from the File Exporter on the machine on which the data resides. If the File Exporter can grant the client's request, it passes the tokens to the client; otherwise, it either queues the request until it can service it or just refuses to grant it. A client that receives the requested tokens can then use them to access the data it wants from the File Exporter.
The following topics provide more detailed information about tokens, their management by the File Exporter, and the token state recovery that occurs after a communications failure between a File Exporter and its clients.
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