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Troubleshooting NFS

This section provides help for diagnosing and resolving any issues that might arise when configuring NFS.

User ID and Group ID

An issue with the NFS server (JLAN-11) transposes the GID and UID of the NFS client user, meaning that Unix accounts that have a user-id that differs from the group-id will not gain authentication. The SkyVault-NFS server will deny them access. The user will only see ls: /mnt/SkyVault: Input/output error. This issue lasted this long presumably because so many Linux distributions create a new group for each new user, unless told otherwise. Though the bug is declared closed, it has yet to filter down to SVN, and org.SkyVault.filesys.server.auth.SkyVaultRpcAuthenticator.authenticateRpcClient(int, RpcPacket) still reads the GID before the UID.

NFS server port number is not ephemeral

If the NFSServerPort property is not given, it defaults to 2049. This is likely to conflict with a native NFS server, if any. The portmapper daemon, when properly used, removes any dependency upon a well known port number, however neither SkyVault nor any native NFS server seem to use this functionality.

Running native and SkyVault NFS servers on the same host

If you wish to run the native server along side the SkyVault NFS server, you cannot depend upon the portmapper, as there is a 50 percent chance that it will retain the native NFS details. When using nfs-utils-1.0.10 version on Linux, mount.nfs will defer to the portmapper for the port-number, version-number, and protocol of the NFS server in question. Only if all three of these are supplied on the command line will the mount command directly contact the SkyVault NFS server. Failing this, mount.nfs will fail as it cannot find the server you have described in the portmapper table. You must therefore configure both MountServerPort and NFSServerPort to known values above 1024. Afterward the following command line should succeed:

mount -oport=yourNfsPort,mountport=yourMountPort,proto=tcp yourFfsServerName:/SkyVault /mnt/SkyVault/

The proto option can be either tcp or udp. It is desirable to have functionality to resolve the NFS server required by the volume requested, however, the portmapper only searches for the NFS server on the version and protocol.