NFS version 4 support

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Beginning with AIX® 5.3, support for NFS version 4 protocol features is included.

The mandatory features of the protocol are supported as described in RFC 3530 with the following exceptions:
  • The LIPKEY and SPKM-3 security mechanisms are not supported with RPCSEC-GSS RPC authentication. Only the Kerberos V5 mechanism is supported.
  • The UTF-8 requirements are not fully supported. Specifically, the transmission of file names and file system strings such as symbolic link contents and directory entry names are not guaranteed to be in UTF-8 format. Transmission of NFS attribute strings, such as owner and owner group, are always in UTF-8 format. The NFS server and client do perform UTF-8 validation on incoming string data as defined RFC 3530. This checking can be administratively disabled using the nfso command. Disabling UTF-8 checking may be necessary to use NFS version 4 in environments with non UTF-8 configurations and data.
  • Diskless client, NIM, and UDP are not supported over NFS version 4.
The following optional features of NFS version 4 are supported:
  • NFS version 4 ACLs are supported by both the NFS client and server. The NFS client supports management of NFS version 4 ACLs using the acledit, aclget, and aclput utilities. The NFS server is capable of storing and retrieving NFS version 4 ACLs in underlying file systems that support the NFS version 4 ACL model. For more information, see NFS Access Control Lists support.
  • Support is provided to map principals and file ownership attributes from one NFS version 4 domain into another. This support is primarily intended for use at AIX NFS servers. It requires deployment of LDAP. The NFS mappings are managed using the chnfsim utility.

There are several considerations when using concurrent access with NFS versions 2 and 3, and NFS version 4. NFS version 3 access may receive errors due to the NFS version 4 granted state. Also, NFS version 3 performance may be impacted when data is exported for NFS version 4 access.