CONFIGURING NFS CLIENTS in Software

Printing Quick Response Code in Software CONFIGURING NFS CLIENTS

NFS clients are remarkably easy to configure under Linux, because they don t require any new or additional software to be loaded The only requirement is that the kernel be compiled to support the NFS file system Virtually all Linux distributions come with this feature enabled by default Aside from the kernel support, the only other important factor is the options used with the mount command

22:

Network File System (NFS)

The mount command was originally discussed in 7 The important parameters to use with the mount command are the specification of the NFS server name, the local mount point, and the options specified after the -o on the mount command line The following is an example of a mount command line:

Here, serverA is the NFS server name The -o options are explained in Table 22-2 These mount options can also be used in the /etc/fstab file This same entry in the /etc/fstab file would look like this:

Again, serverA is the NFS server name, and the mount options are rw, bg and soft, explained in Table 22-2

Description Background mount Should the mount initially fail (for instance, if the server is down), the mount process will send itself to background processing and continue trying to execute until it is successful This is useful for file systems mounted at boot time, because it keeps the system from hanging at the mount command if the server is down Specifies an interruptible mount If a process has pending I/O on a mounted partition, this option allows the process to be interrupted and the I/O call to be dropped For more information, see The Importance of the intr Option, later in this section This is an implicit default option If an NFS file operation has a major timeout, then a server not responding message is reported on the console and the client continues retrying indefinitely

Description Enables a soft mount for this partition, allowing the client to time out the connection after a number of retries (specified with the retrans=r option) For more information, see Soft vs Hard Mounts, later in this section The value n specifies the maximum number of connection retries for a soft-mounted system The value n is the number of bytes NFS uses when reading files from an NFS server The default value is dependent on the kernel, but is currently 4096 bytes for NFSv4 Throughput can be improved greatly by requesting a higher value (eg, rsize=32768) The value n specifies the number of bytes NFS uses when writing files to an NFS server The default value is dependent on the kernel, but is currently something like 4096 bytes for NFSv4 Throughput can be greatly improved by asking for a higher value (eg, wsize=32768) This value is negotiated with the server The value n specifies the network protocol to use to mount the NFS file system The default value in NFSv2 and NFSv3 is UDP NFSv4 servers generally support only TCP Therefore, the valid protocol types are udp and tcp Allows the use of an alternate RPC version number to contact the NFS daemon on the remote host The default value depends on the kernel, but the possible values are 2 and 3 This option is not recognized in NFSv4, where instead, you d simply state nfs4 as the file system type

Table 22-2 Mount Options for NFS (cont)

22:

Network File System (NFS)

Description Sets the security mode for the mount operation to value: sec=sys Uses local UNIX UIDs and GIDs to authenticate NFS operations (AUTH_SYS) This is the default setting sec=krb5 Uses Kerberos V5 instead of local UIDs and GIDs to authenticate users sec=krb5i Uses Kerberos V5 for user authentication and performs integrity checking of NFS operations using secure checksums to prevent data tampering

sec=krb5p Uses Kerberos V5 for user authentication and integrity checking, and encrypts NFS traffic to prevent traffic sniffing

Table 22-2 Mount Options for NFS (cont)