mounting a file system over NFSv3

The following occurs when mounting a file system over NFSv3.

1. RPC is made to port 111 (portmapper) of the NFS server to attempt a TCP connection through the

portmapper.

 

2. When the RPC call has been acknowledged, portmapper issues a GETPORT call to port 111 of the

NFS server data LIF to obtain which port NFS is allowed on.

 

3. The NFS server returns the port 2049 (NFS) to the client.

 

4. The client then closes the connection to port 111.

 

5. A new RPC call is made to port 2049 of the NFS server data LIF.

 

6. The NFS server returns the call successfully, and the client sends an NFS NULL call to port 2049 of

the NFS server’s data LIF. This checks whether the parent volume allows access to the mount. In this

case, the parent volume is mounted to /, or the SVM root.

 

7. The NFS NULL call is returned successfully, and the client proceeds with the mount attempt.

 

8. Portmapper sends a GETPORT call to the NFS server’s data LIF asking for the mountd port and

provides the credentials, NFS version number, and whether the mount uses TCP or UDP.

 

9. The cluster checks the NFS settings and verifies whether the credentials supplied are allowed to

mount based on the export policy rules. This is done through an RPC call from the NAS blade to the

SecD process. If SecD is not functioning properly, this check fails, and the mount gets access

denied. If the NFS version or TCP/UDP is not allowed, the client reports the error.

 

10. The NFS server replies successfully if the version provided is supported and if the mount can use the

specified TCP or UDP connection. It also replies if the AUTH security provider is supported

(AUTH_SYS or AUTH_GSS, for example).

 

11. When the GETPORT call passes, the client issues a V3 MNT call to the junction path specified in the

mount command through port 635 (mountd) of the NFS server data LIF.

 

12. The cluster uses the junction path provided by the client and searches for the path in the volume

location database (vldb). If the entry exists, the cluster gathers the file handle information from the

vldb.

 

13. The NFS server returns the file handle to the client, as well as replies which AUTH varieties are

supported by the export policy rule. If the AUTH variety provided by the server matches what the

client sent, the mount succeeds.

 

14. Portmapper from the client then sends another GETPORT call for NFS, this time providing the client’s

host name.

 

15. The NFS server replies with port 2049, and the call succeeds.

 

16. Another NFS NULL call is made from the client over port 2049 of the NFS data LIF and is

acknowledged by the NFS server.

 

17. A series of NFS packets with FSINFO and PATHCONF information is traded between the client and

the NFS server.