| .\" nfs.5 "Rick Sladkey" <jrs@world.std.com> |
| .\" Wed Feb 8 12:52:42 1995, faith@cs.unc.edu: updates for Ross Biro's |
| .\" patches. " |
| .TH NFS 5 "20 November 1993" "Linux 0.99" "Linux Programmer's Manual" |
| .SH NAME |
| nfs \- nfs fstab format and options |
| .SH SYNOPSIS |
| .B /etc/fstab |
| .SH DESCRIPTION |
| The |
| .I fstab |
| file contains information about which filesystems |
| to mount where and with what options. |
| For NFS mounts, it contains the server name and |
| exported server directory to mount from, |
| the local directory that is the mount point, |
| and the NFS specific options that control |
| the way the filesystem is mounted. |
| .P |
| Here is an example from an \fI/etc/fstab\fP file from an NFS mount. |
| .sp |
| .nf |
| .ta 2.5i +0.75i +0.75i +1.0i |
| server:/usr/local/pub /pub nfs rsize=8192,wsize=8192,timeo=14,intr |
| .fi |
| .DT |
| .SS Options |
| .TP 1.5i |
| .I rsize=n |
| The number of bytes NFS uses when reading files from an NFS server. |
| The default value is dependent on the kernel, currently 1024 bytes. |
| (However, throughput is improved greatly by asking for |
| .IR rsize=8192 .) |
| .TP 1.5i |
| .I wsize=n |
| The number of bytes NFS uses when writing files to an NFS server. |
| The default value is dependent on the kernel, currently 1024 bytes. |
| (However, throughput is improved greatly by asking for |
| .IR wsize=8192 .) |
| .TP 1.5i |
| .I timeo=n |
| The value in tenths of a second before sending the |
| first retransmission after an RPC timeout. |
| The default value is 7 tenths of a second. After the first timeout, |
| the timeout is doubled after each successive timeout until a maximum |
| timeout of 60 seconds is reached or the enough retransmissions |
| have occured to cause a major timeout. Then, if the filesystem |
| is hard mounted, each new timeout cascade restarts at twice the |
| initial value of the previous cascade, again doubling at each |
| retransmission. The maximum timeout is always 60 seconds. |
| Better overall performance may be achieved by increasing the |
| timeout when mounting on a busy network, to a slow server, or through |
| several routers or gateways. |
| .TP 1.5i |
| .I retrans=n |
| The number of minor timeouts and retransmissions that must occur before |
| a major timeout occurs. The default is 3 timeouts. When a major timeout |
| occurs, the file operation is either aborted or a "server not responding" |
| message is printed on the console. |
| .TP 1.5i |
| .I acregmin=n |
| The minimum time in seconds that attributes of a regular file should |
| be cached before requesting fresh information from a server. |
| The default is 3 seconds. |
| .TP 1.5i |
| .I acregmax=n |
| The maximum time in seconds that attributes of a regular file can |
| be cached before requesting fresh information from a server. |
| The default is 60 seconds. |
| .TP 1.5i |
| .I acdirmin=n |
| The minimum time in seconds that attributes of a directory should |
| be cached before requesting fresh information from a server. |
| The default is 30 seconds. |
| .TP 1.5i |
| .I acdirmax=n |
| The maximum time in seconds that attributes of a directory can |
| be cached before requesting fresh information from a server. |
| The default is 60 seconds. |
| .TP 1.5i |
| .I actimeo=n |
| Using actimeo sets all of |
| .I acregmin, |
| .I acregmax, |
| .I acdirmin, |
| and |
| .I acdirmax |
| to the same value. |
| There is no default value. |
| .TP 1.5i |
| .I retry=n |
| The number of minutes to retry an NFS mount operation |
| in the foreground or background before giving up. |
| The default value is 10000 minutes, which is roughly one week. |
| .TP 1.5i |
| .I namlen=n |
| When an NFS server does not support version two of the |
| RPC mount protocol, this option can be used to specify |
| the maximum length of a filename that is supported on |
| the remote filesystem. This is used to support the |
| POSIX pathconf functions. The default is 255 characters. |
| .TP 1.5i |
| .I port=n |
| The numeric value of the port to connect to the NFS server on. |
| If the port number is 0 (the default) then query the |
| remote host's portmapper for the port number to use. |
| If the remote host's NFS daemon is not registered with |
| its portmapper, the standard NFS port number 2049 is |
| used instead. |
| .TP 1.5i |
| .I mountport=n |
| The numeric value of the |
| .B mountd |
| port. |
| .TP 1.5i |
| .I mounthost=name |
| The name of the host running |
| .B mountd . |
| .TP 1.5i |
| .I mountprog=n |
| Use an alternate RPC program number to contact the |
| mount daemon on the remote host. This option is useful |
| for hosts that can run multiple NFS servers. |
| The default value is 100005 which is the standard RPC |
| mount daemon program number. |
| .TP 1.5i |
| .I mountvers=n |
| Use an alternate RPC version number to contact the |
| mount daemon on the remote host. This option is useful |
| for hosts that can run multiple NFS servers. |
| The default value is version 1. |
| .TP 1.5i |
| .I nfsprog=n |
| Use an alternate RPC program number to contact the |
| NFS daemon on the remote host. This option is useful |
| for hosts that can run multiple NFS servers. |
| The default value is 100003 which is the standard RPC |
| NFS daemon program number. |
| .TP 1.5i |
| .I nfsvers=n |
| Use an alternate RPC version number to contact the |
| NFS daemon on the remote host. This option is useful |
| for hosts that can run multiple NFS servers. |
| The default value is version 2. |
| .TP 1.5i |
| .I nolock |
| Disable NFS locking. This has to be used with some old NFS servers |
| that don't support locking. |
| .TP 1.5i |
| .I bg |
| If the first NFS mount attempt times out, retry the mount |
| in the background. |
| After a mount operation is backgrounded, all subsequent mounts |
| on the same NFS server will be backgrounded immediately, without |
| first attempting the mount. |
| A missing mount point is treated as a timeout, |
| to allow for nested NFS mounts. |
| .TP 1.5i |
| .I fg |
| If the first NFS mount attempt times out, retry the mount |
| in the foreground. |
| This is the complement of the |
| .I bg |
| option, and also the default behavior. |
| .TP 1.5i |
| .I soft |
| If an NFS file operation has a major timeout then report an I/O error to |
| the calling program. |
| The default is to continue retrying NFS file operations indefinitely. |
| .TP 1.5i |
| .I hard |
| If an NFS file operation has a major timeout then report |
| "server not responding" on the console and continue retrying indefinitely. |
| This is the default. |
| .TP 1.5i |
| .I intr |
| If an NFS file operation has a major timeout and it is hard mounted, |
| then allow signals to interupt the file operation and cause it to |
| return EINTR to the calling program. The default is to not |
| allow file operations to be interrupted. |
| .TP 1.5i |
| .I posix |
| Mount the NFS filesystem using POSIX semantics. This allows |
| an NFS filesystem to properly support the POSIX pathconf |
| command by querying the mount server for the maximum length |
| of a filename. To do this, the remote host must support version |
| two of the RPC mount protocol. Many NFS servers support only |
| version one. |
| .TP 1.5i |
| .I nocto |
| Suppress the retrieval of new attributes when creating a file. |
| .TP 1.5i |
| .I noac |
| Disable all forms of attribute caching entirely. This extracts a |
| server performance penalty but it allows two different NFS clients |
| to get reasonable good results when both clients are actively |
| writing to common filesystem on the server. |
| .TP 1.5i |
| .I nolock |
| Do not use locking. Do not start lockd. |
| .TP 1.5i |
| .I tcp |
| Mount the NFS filesystem using the TCP protocol instead of the |
| default UDP protocol. Many NFS severs only support UDP. |
| .TP 1.5i |
| .I udp |
| Mount the NFS filesystem using the UDP protocol. This |
| is the default. |
| .P |
| All of the non-value options have corresponding nooption forms. |
| For example, nointr means don't allow file operations to be |
| interrupted. |
| .SH FILES |
| .I /etc/fstab |
| .SH "SEE ALSO" |
| .BR fstab "(5), " mount "(8), " umount "(8), " exports (5) |
| .SH AUTHOR |
| "Rick Sladkey" <jrs@world.std.com> |
| .SH BUGS |
| The posix, and nocto options are parsed by mount |
| but currently are silently ignored. |
| .P |
| The tcp and namlen options are implemented but are not currently |
| supported by the Linux kernel. |
| .P |
| The umount command should notify the server |
| when an NFS filesystem is unmounted. |