File system name space
NFSv4 provides a different model file system name-space model than did previous versions. Servers, rather than exporting multiple file systems, export a single "pseudo file system," formed from multiple actual file systems, and potentially customized for each client.
NFSv4 as a stateful protocol
Previous NFS protocols were stateless in the sense that the NFS server maintained no information or state about its clients.NFSv4, however, is stateful; the NFSv4 server maintains information about its clients, the files they hold open, and locks.Using stateful design enhance performance and scalability.
Delegation
Clients may perform operations on files with minimal interaction with the server. NFSv4 introduces file delegation. An NFSv4 server can allow an NFSv4 client to access and modify a file in it's own cache without sending any network requests to the server, until the server indicates via a callback that another client wishes to access a file. This reduces the amount of traffic between NFSv4 client and server considerably in cases where no other clients wish to access a set of files concurrently.
Security
A strong security model is mandated, where client/server interactions are done using the GSS-API framework. Three security mechanisms are needed: Kerberos, LIPKEY, and SPKM-3. Which one is actually used is negotiated between client and server. Security principals are now given as strings (e.g., user@domain) rather than as user IDs as was done in the earlier versions. Authorization uses both standard UNIX-like permissions as well as Windows ACLs.
NFSv4 provides a different model file system name-space model than did previous versions. Servers, rather than exporting multiple file systems, export a single "pseudo file system," formed from multiple actual file systems, and potentially customized for each client.
NFSv4 as a stateful protocol
Previous NFS protocols were stateless in the sense that the NFS server maintained no information or state about its clients.NFSv4, however, is stateful; the NFSv4 server maintains information about its clients, the files they hold open, and locks.Using stateful design enhance performance and scalability.
Delegation
Clients may perform operations on files with minimal interaction with the server. NFSv4 introduces file delegation. An NFSv4 server can allow an NFSv4 client to access and modify a file in it's own cache without sending any network requests to the server, until the server indicates via a callback that another client wishes to access a file. This reduces the amount of traffic between NFSv4 client and server considerably in cases where no other clients wish to access a set of files concurrently.
Security
A strong security model is mandated, where client/server interactions are done using the GSS-API framework. Three security mechanisms are needed: Kerberos, LIPKEY, and SPKM-3. Which one is actually used is negotiated between client and server. Security principals are now given as strings (e.g., user@domain) rather than as user IDs as was done in the earlier versions. Authorization uses both standard UNIX-like permissions as well as Windows ACLs.
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