Mount NFS Share on CentOS 5: NFSv3 Client with portmap, fstab and RPC Troubleshooting

This guide mounts an NFS share on a CentOS 5 client. CentOS 5 uses the older RPC stack: portmap instead of rpcbind, and NFSv3 when you mount with -t nfs. Most of the troubleshooting below comes down to RPC.

On CentOS 6? Use Mount NFS Share on CentOS 6: rpcbind, NFSv4 Defaults, idmapd and fstab instead. CentOS 6 replaced portmap with rpcbind and tries NFSv4 first, so the services and some fixes are different.

1. Install the client packages

yum install nfs-utils portmap

2. Start portmap and the lock service

NFSv3 needs portmap for RPC and nfslock (rpc.statd) for file locking:

service portmap start
chkconfig portmap on
service nfslock start
chkconfig nfslock on

3. Check the server before mounting

rpcinfo -p 192.168.1.112
showmount -e 192.168.1.112

rpcinfo should list portmapper, mountd and nfs. showmount -e lists the exported paths.

4. Create a mount point and mount

mkdir /mnt/NFS
mount -t nfs 192.168.1.112:/NFS /mnt/NFS

Check it with df -h. The remote share shows up like a local disk:

5. Make it permanent in /etc/fstab

Otherwise the mount is gone after the next reboot. Add a line like this:

192.168.1.112:/NFS   /mnt/NFS   nfs   defaults   0 0

For a share that must not hang processes forever, hard,intr is the classic CentOS 5 choice. The 2.6.18 kernel still lets you interrupt a hung NFS operation with Ctrl+C when intr is set. Also enable netfs so network filesystems mount at boot once the network is up:

chkconfig netfs on

Test the fstab entry without rebooting. This mounts everything in fstab that isn’t mounted yet, so do it in a maintenance window:

mount -a

Troubleshooting RPC mount errors

• “mount: RPC: Port mapper failure – RPC: Unable to receive”: portmap isn’t running on one side, or a firewall is blocking port 111.
• “RPC: Program not registered”: the NFS service isn’t running on the server. Check with rpcinfo -p server.
• “mount: … failed, reason given by server: Permission denied”: the client isn’t allowed in /etc/exports. Run exportfs -ra on the server after fixing it.
• Hangs on mount through a firewall: mountd and statd use random ports. Pin them in /etc/sysconfig/nfs on the server and open those ports.

Unmount

umount /mnt/NFS

The command is umount, not “unmount”. I’ve made that mistake thousands of times. For the server side on this release, see Configure NFS for CentOS 5.

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Related guides: Mount NFS Share on CentOS 6: rpcbind, NFSv4 Defaults, idmapd and fstab | Configure NFS for CentOS 5