MAN page from Scientific Linux Other mount-2.11y-31.24.i386.rpm

NFS

Section: Linux Programmer's Manual (5)
Updated: 20 November 1993
Index

NAME

nfs - nfs fstab format and options

SYNOPSIS

/etc/fstab

DESCRIPTION

Thefstabfile contains information about which filesystemsto mount where and with what options.For NFS mounts, it contains the server name andexported server directory to mount from,the local directory that is the mount point,and the NFS specific options that controlthe way the filesystem is mounted.

Here is an example from an /etc/fstab file from an NFS mount.

server:/usr/local/pub    /pub    nfs     rsize=8192,wsize=8192,timeo=14,intr

Options

rsize=n: The number of bytes NFS uses when reading files from an NFS server.The rsize is negotiated between the server and client to determine the largest block size that both can support.The value specified by this option is the maximum size that could be used; however, the actual size used may be smaller.Note: Setting this size to a value less than the largest supportedblock size will adversely affect performance.
wsize=n: The number of bytes NFS uses when writing files to an NFS server.The wsize is negotiated between the server and client to determine the largest block size that both can support.The value specified by this option is the maximum size that could be used; however, the actual size used may be smaller.Note: Setting this size to a value less than the largest supportedblock size will adversely affect performance.
timeo=n: The value in tenths of a second before sending thefirst 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 maximumtimeout of 60 seconds is reached or the enough retransmissionshave occured to cause a major timeout. Then, if the filesystemis hard mounted, each new timeout cascade restarts at twice theinitial value of the previous cascade, again doubling at eachretransmission. The maximum timeout is always 60 seconds.Better overall performance may be achieved by increasing thetimeout when mounting on a busy network, to a slow server, or throughseveral routers or gateways.
retrans=n: The number of minor timeouts and retransmissions that must occur beforea major timeout occurs. The default is 3 timeouts. When a major timeoutoccurs, the file operation is either aborted or a "server not responding"message is printed on the console.
acregmin=n: The minimum time in seconds that attributes of a regular file shouldbe cached before requesting fresh information from a server.The default is 3 seconds.
acregmax=n: The maximum time in seconds that attributes of a regular file canbe cached before requesting fresh information from a server.The default is 60 seconds.
acdirmin=n: The minimum time in seconds that attributes of a directory shouldbe cached before requesting fresh information from a server.The default is 30 seconds.
acdirmax=n: The maximum time in seconds that attributes of a directory canbe cached before requesting fresh information from a server.The default is 60 seconds.
actimeo=n: Using actimeo sets all ofacregmin,acregmax,acdirmin,andacdirmaxto the same value.There is no default value.
retry=n: The number of minutes to retry an NFS mount operationin the foreground or background before giving up.The default value for background mounts are 10000 minutes, which is roughly one week. The default value for foreground mounts is three retries, waiting 30 seconds between each try.
namlen=n: When an NFS server does not support version two of theRPC mount protocol, this option can be used to specifythe maximum length of a filename that is supported onthe remote filesystem. This is used to support thePOSIX pathconf functions. The default is 255 characters.
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 theremote host's portmapper for the port number to use.If the remote host's NFS daemon is not registered withits portmapper, the standard NFS port number 2049 isused instead.
mountport=n: The numeric value of themountdport.
mounthost=name: The name of the host runningmountd .
mountprog=n: Use an alternate RPC program number to contact themount daemon on the remote host. This option is usefulfor hosts that can run multiple NFS servers.The default value is 100005 which is the standard RPCmount daemon program number.
mountvers=n: Use an alternate RPC version number to contact themount daemon on the remote host. This option is usefulfor hosts that can run multiple NFS servers.The default value is version 1.
nfsprog=n: Use an alternate RPC program number to contact theNFS daemon on the remote host. This option is usefulfor hosts that can run multiple NFS servers.The default value is 100003 which is the standard RPCNFS daemon program number.
nfsvers=n: Use an alternate RPC version number to contact theNFS daemon on the remote host. This option is usefulfor hosts that can run multiple NFS servers.The default value is version 2.
nolock: Disable NFS locking. Do not start lockd.This has to be used with some old NFS serversthat don't support locking.
bg: If the first NFS mount attempt times out, retry the mountin the background.After a mount operation is backgrounded, all subsequent mountson the same NFS server will be backgrounded immediately, withoutfirst attempting the mount.A missing mount point is treated as a timeout,to allow for nested NFS mounts.
fg: If the first NFS mount attempt times out, retry the mountin the foreground.This is the complement of thebgoption, and also the default behavior.
soft: If an NFS file operation has a major timeout then report an I/O error tothe calling program.The default is to continue retrying NFS file operations indefinitely.
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.
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 toreturn EINTR to the calling program. The default is to notallow file operations to be interrupted.
posix: Mount the NFS filesystem using POSIX semantics. This allowsan NFS filesystem to properly support the POSIX pathconfcommand by querying the mount server for the maximum lengthof a filename. To do this, the remote host must support versiontwo of the RPC mount protocol. Many NFS servers support onlyversion one.
nocto: Suppress the retrieval of new attributes when creating a file.
noac: Disable all forms of attribute caching entirely. This extracts aserver performance penalty but it allows two different NFS clientsto get reasonable good results when both clients are activelywriting to common filesystem on the server.
noacl: Disables Access Control List (ACL) processing.
tcp: Mount the NFS filesystem using the TCP protocol instead of thedefault UDP protocol. Many NFS servers only support UDP.
udp: Mount the NFS filesystem using the UDP protocol. Thisis the default.