Common Problems with NFS

Enter the /usr/sbin/ping command on the NFS client to make sure the NFS server is up and is reachable on the network. If the ping command fails, either the server is down, or the network has a problem. If the server is down, reboot it, or wait for it to come back up. For more information on troubleshooting network problems, see HP-UX LAN Administrator's Guide.

Ensure that the following daemons are running on the NFS server:

Enter the following command on the NFS client to make sure the server is running all the NFS server processes:

/usr/bin/rpcinfo -p servername

The rpcinfo command should display the following services:

On the NFS server, check if the following processes are running:

If any of these processes is not running, follow these steps:

Enter the following command on the NFS client to make sure the rpc.mountd process on the NFS server is available and responding to RPC requests:

/usr/bin/rpcinfo -u servername mountd

If the rpcinfo command returns RPC_TIMED_OUT, the rpc.mountd process may be hung. Enter the following commands on the NFS server to restart rpc.mountd (PID is the process ID returned by the ps command):

/usr/bin/ps -ef | /usr/bin/grep mountd
/usr/bin/kill PID
/usr/sbin/rpc.mountd

You can receive “server not responding” messages when the server or network is heavily loaded and the RPC requests are timing out.

	NOTE: For TCP, the default timeout is 600 while for UDP, the default timeout is 11.

Try doubling the timeo mount option for the directory, as in the following example from the /etc/fstab file, which changes the timeo value from 600 (the default) to 1200. (The timeo option is in tenths of a second.)

cabbage:/usr /usr nfs nosuid,timeo=1200 0 0

Enter the following command on the NFS client to check that your hosts database returns the correct address for the NFS server:

/usr/bin/nslookup server_name

Enter the same nslookup command on the NFS server, and compare the address with the one returned by the nslookup command on the NFS client. If they are different, correct your NIS, BIND, or /etc/hosts configuration. For information on BIND or /etc/hosts, see Installing and Administering Internet Services (B2355-91060).

If you are using AutoFS, enter the ps -ef command to make sure the automountd process is running on your NFS client. If it is not, follow these steps:

Enter the following command on the NFS client to check that the NFS server is exporting the directory you want to mount:

/usr/sbin/showmount -e server_name

If the server is not exporting the directory, edit the /etc/dfs/dfstab file on the server so that it allows your NFS client access to the directory. Then, enter the following command to force the server to read its /etc/dfs/dfstab file.

shareall -F nfs

If the directory is shared with the [access_list] option, make sure your NFS client is included in the [access_list], either individually or as a member of a netgroup.

Enter the following commands on the NFS server to make sure your NFS client is listed in its hosts database:

nslookup client_name
nslookup client_IP_address

Check the mount options in the /etc/fstab file on the NFS client. A directory you are attempting to write to may have been mounted as read-only.

Enter the ls -l command to check the HP-UX permissions on the server directory and on the client directory that is the mount point. You may not be allowed access to the directory.

Enter the following command on the NFS server:

/usr/sbin/share

Or, enter the following command on the NFS client:

/usr/sbin/showmount -e server_name

Check the permissions on the shared directory. The directory may have been shared as read-only to your client. The administrator of the NFS server can use the remount mount option to mount the directory read/write without unmounting it. See “Changing the Default Mount Options”“Changing the Default Mount Options” on page 51.

If you are logged in as root to the NFS client, check the share permissions to determine whether root access to the directory is granted to your NFS client.

If you are logged in as root to the NFS client, and your client is not allowed root access to the exported directory, check the passwd database on the NFS server to determine whether it contains an entry for user nobody. Without root access, the root user on an NFS client is given the access permissions of an anonymous user. Also, check whether anonymous users are denied access to the directory (with the anon=65535 export option).

If your client is not allowed root access or anonymous user ID access to the exported directory, log in as a non-root user to get access to the directory.

If you were attempting to run a program when you received the “permission denied” message, enter the ls -l command on the NFS server to check whether the program you tried to run has the setuid bit set. If it does, check /etc/fstab to determine whether the directory was mounted with the nosuid mount option. If necessary, remove the nosuid option from the /etc/fstab file, then unmount and remount the directory.

If you received the “device busy” message while attempting to mount a directory, check whether it is already mounted.

If you received the “device busy” message while attempting to unmount a directory, a user or process is currently using the directory. Wait until the process completes, or follow these steps:

Verify that the filesystem you are trying to unmount is not a mount-point of another filesystem.

Verify that the filesystem is not exported. In HP-UX 11i v3, an exported filesystem keeps the filesystem busy.

If the stale file handle occurred because someone removed a file or directory that was in use, or because a server stopped exporting a directory that was in use, follow these steps:

If someone has restored the server’s file systems from backup or entered the fsirand command on the server, follow these steps on each of the NFS clients to prevent stale file handles by restarting NFS:

Check whether the NFS server is up and operating correctly. If you are not sure, see “NFS “Server Not Responding” Message”.

If the server is down, wait until it comes back up, or, if the directory was mounted with the intr mount option (the default), you can interrupt the NFS mount, usually with CTRL-C.

If the program uses file locking, enter the following commands (on either the client or the server) to make sure rpc.statd and rpc.lockd are available and responding to RPC requests:

/usr/bin/rpcinfo -u servername status
/usr/bin/rpcinfo -u servername nlockmgr
/usr/bin/rpcinfo -u clientname status
/usr/bin/rpcinfo -u clientname nlockmgr

If any of these commands return RPC_TIMED_OUT, the rpc.statd or rpc.lockd process may be hung. Follow these steps to restart rpc.statd and rpc.lockd daemons:

Make sure that the directory is not exported from the server with the async option. If the directory is exported with the async option, the NFS server will acknowledge NFS writes before actually writing data to disk.

If users or applications are writing to the NFS-mounted directory, make sure it is mounted with the hard option (the default), rather than the soft option.

If you have a small number of NFS applications that require absolute data integrity, add the O_SYNC flag to the open() calls in your applications. When you open a file with the O_SYNC flag, a write() call will not return until the write request has been sent to the NFS server and acknowledged. The O_SYNC flag degrades write performance for applications that use it.

If multiple NFS users are writing to the same file, add the lockf() call to your applications to lock the file so that only one user may modify it at a time.

If multiple users on different NFS clients are writing to the file, you must also turn off attribute caching on those clients by mounting the file with the noac mount option. Turning off attribute caching degrades NFS performance.