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148 Stars 58 Forks Other 1.2K Commits 25 Opened issues


Pure Java NFSv3 and NFSv4.1 implementation

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Latest release

The pure java implementation of NFS server version 3, 4.0 and 4.1 including pNFS extension with nfs4.1-files and flex-files layout types.

Building from sources

To build nfs4j from source code Java11 and Maven3 are required.

To run benchmarks:

mvn verify -Pbenchmark

Implementing own NFS server

public class App {

public static void main(String[] args) throws Exception {

    // create an instance of a filesystem to be exported
    VirtualFileSystem vfs = new ....;

    // create the RPC service which will handle NFS requests
    OncRpcSvc nfsSvc = new OncRpcSvcBuilder()

    // specify file with export entries
    ExportFile exportFile = new ExportFile(....);

    // create NFS v4.1 server
    NFSServerV41 nfs4 = new NFSServerV41.Builder()
            .withOperationFactory(new MDSOperationFactory())

    // create NFS v3 and mountd servers
    NfsServerV3 nfs3 = new NfsServerV3(exportFile, vfs);
    MountServer mountd = new MountServer(exportFile, vfs);

    // register NFS servers at portmap service
    nfsSvc.register(new OncRpcProgram(100003, 4), nfs4);
    nfsSvc.register(new OncRpcProgram(100003, 3), nfs3);
    nfsSvc.register(new OncRpcProgram(100005, 3), mountd);

    // start RPC service


Use NFS4J in your project


        dCache.ORG maven repository


Though NFS4J is used by the dCache and other projects in production, the public API is still unstable and subject to change (indicated by leading zero in the version number). Thus, should be considered as


Please consult the API changes document when switching between version numbers. The patch level releases are not affected by API changes, of course.


licensed under LGPLv2 (or later)

How to contribute

NFS4J uses the linux kernel model where git is not only source repository, but also the way to track contributions and copyrights.

Each submitted patch must have a "Signed-off-by" line. Patches without this line will not be accepted.

The sign-off is a simple line at the end of the explanation for the patch, which certifies that you wrote it or otherwise have the right to pass it on as an open-source patch. The rules are pretty simple: if you can certify the below:

    Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
     have the right to submit it under the open source license
     indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

then you just add a line saying ( git commit -s )

Signed-off-by: Random J Developer 

using your real name (sorry, no pseudonyms or anonymous contributions.)

Contact Us

For help and development related discussions please contact us: dev (@) dcache (.) org

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