Installation guide

Chapter 10. Network File System (NFS)
66
10.4. Common NFS Mount Options
Beyond mounting a file system via NFS on a remote host, you can also specify other options at
mount time to make the mounted share easier to use. These options can be used with manual mount
commands, /etc/fstab settings, and autofs.
The following are options commonly used for NFS mounts:
intr
Allows NFS requests to be interrupted if the server goes down or cannot be reached.
lookupcache=mode
Specifies how the kernel should manage its cache of directory entries for a given mount point.
Valid arguments for mode are all, none, or pos/positive.
nfsvers=version
Specifies which version of the NFS protocol to use, where version is 2, 3, or 4. This is useful
for hosts that run multiple NFS servers. If no version is specified, NFS uses the highest version
supported by the kernel and mount command.
The option vers is identical to nfsvers, and is included in this release for compatibility reasons.
noacl
Turns off all ACL processing. This may be needed when interfacing with older versions of Red
Hat Enterprise Linux, Red Hat Linux, or Solaris, since the most recent ACL technology is not
compatible with older systems.
nolock
Disables file locking. This setting is occasionally required when connecting to older NFS servers.
noexec
Prevents execution of binaries on mounted file systems. This is useful if the system is mounting a
non-Linux file system containing incompatible binaries.
nosuid
Disables set-user-identifier or set-group-identifier bits. This prevents remote users
from gaining higher privileges by running a setuid program.
port=num
port=num — Specifies the numeric value of the NFS server port. If num is 0 (the default), then
mount queries the remote host's rpcbind service for the port number to use. If the remote host's
NFS daemon is not registered with its rpcbind service, the standard NFS port number of TCP
2049 is used instead.
rsize=num and wsize=num
These settings speed up NFS communication for reads (rsize) and writes (wsize) by setting
a larger data block size (num, in bytes), to be transferred at one time. Be careful when changing
these values; some older Linux kernels and network cards do not work well with larger block sizes.
For NFSv2 or NFSv3, the default values for both parameters is set to 8192. For NFSv4, the default
values for both parameters is set to 32768.
sec=mode
Specifies the type of security to utilize when authenticating an NFS connection. Its default setting
is sec=sys, which uses local UNIX UIDs and GIDs by using AUTH_SYS to authenticate NFS
operations.
sec=krb5 uses Kerberos V5 instead of local UNIX UIDs and GIDs to authenticate users.