Linux : mount.nfs: Input/output error

Problem:

Red Hat 5

# mount /u00
mount.nfs: Input/output error

Solution :
service portmap start
chkconfig portmap on
chkconfig nfs on
chkconfig netfs on

Linux : mount.nfs: rpc.statd is not running but is required for remote locking

Problem:

# mount -t nfs 10.10.100.20:/vol/test1/NFSDS01 /mnt
mount.nfs: rpc.statd is not running but is required for remote locking.
mount.nfs: Either use '-o nolock' to keep locks local, or start statd.
mount.nfs: an incorrect mount option was specified

But rpc.statd is running
$ ps -ef | grep rpc.statd
rpcuser 2578 1 0 16:18 ? 00:00:00 rpc.statd
rpcuser 4824 1 0 16:21 ? 00:00:00 rpc.statd --no-notify
rpcuser 4867 1 0 16:22 ? 00:00:00 rpc.statd --no-notify
rpcuser 9287 1 0 17:05 ? 00:00:00 rpc.statd --no-notify
rpcuser 10235 1 0 17:15 ? 00:00:00 rpc.statd --no-notify

Solution:

vi /etc/hosts.allow

rpcbind portmap nfsd statd mountd lockd: 127.0.0.1 10.10.100.20 : ALLOW

Linux : NFS : Some NFS file systems are not mounted after reboot

Problem : Some NFS file systems are not mounted after reboot

Solution : Add options to /etc/fstab

Original fstab :

10.11.200.101:/test /test           nfs     rw      0 0

After :
10.11.200.101:/test /test           nfs     rw,bg,hard,rsize=32768,wsize=32768,vers=3      0 0

Also the following services need to be turned on

chkconfig nfs on
chkconfig portmap on
chkconfig netfs on