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


Here is an example for an NFSv4 mount over TCP using Kerberos


5 mutual authentication.




  

server:/usr/local/pub /pub nfs4 proto=tcp,sec=krb5,hard,intr


  Options for the nfs file system type

 
    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


  rsize=8192 .)

 
 
 
    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


  wsize=8192 .)

 
 
 
    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.


 
 
    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.


 
 
    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.


 
 
    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.


 
 
    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.


 
 
    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.


 
 
    actimeo=n

 
 Using actimeo sets all of


  acregmin,

   acregmax,

   acdirmin,

 and


  acdirmax

 to the same value.


There is no default value.


 
 
    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.


 
 
    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.


 
 
    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.


 
 
    mountport=n

 
 The numeric value of the


  mountd port.


 
 
    mounthost=name

 
 The name of the host running


  mountd . 
 
 
    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.


 
 
    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 depends on which kernel you are using.


 
 
    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.


 
 
    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 depends on which kernel you are using.


 
 
    vers=n

 
 vers is an alternative to nfsvers and is compatible with


many other operating systems.


 
 
    nolock

 
 Disable NFS locking. Do not start lockd.


This has to be used with some old NFS servers


that don't support locking.


 
 
    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.


 
 
    fg

 
 If the first NFS mount attempt times out, retry the mount


in the foreground.


This is the complement of the


  bg

 option, and also the default behavior.


 
 
    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.


 
 
    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 to


return EINTR to the calling program.  The default is to not


allow file operations to be interrupted.


 
 
    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.


 
 
    nocto

 
 Suppress the retrieval of new attributes when creating a file.


 
 
    noac

 
 Disable all forms of attribute caching entirely.  This extracts a


significant performance penalty but it allows two different NFS clients


to get reasonable results when both clients are actively


writing to a common export on the server.


 
 
    sec=mode

 
 Set the security flavor for this mount to "mode".


The default setting is <3>sec=sys<1>, which uses local


unix uids and gids to authenticate NFS operations (AUTH_SYS).


Other currently supported settings are:


<3>sec=krb5<1>, which uses Kerberos V5 instead of local unix uids


and gids to authenticate users;


<3>sec=krb5i<1>, which uses Kerberos V5 for user authentication


and performs integrity checking of NFS operations using secure


checksums to prevent data tampering; and


<3>sec=krb5p<1>, which uses Kerberos V5 for user authentication


and integrity checking, and encrypts NFS traffic to prevent


traffic sniffing (this is the most secure setting).


Note that there is a performance penalty when using integrity


or privacy.


 
 
    tcp

 
 Mount the NFS filesystem using the TCP protocol instead of the


default UDP protocol.  Many NFS servers only support UDP.


 
 
    udp

 
 Mount the NFS filesystem using the UDP protocol.  This


is the default.


All of the non-value options have corresponding nooption forms.


For example, nointr means don't allow file operations to be


interrupted.


  Options for the nfs4 file system type

 
 
 
    rsize=n

 
 The number of bytes NFS uses when reading files from an NFS server.


The default value is dependent on the kernel, currently 4096 bytes.


(However, throughput is improved greatly by asking for


  rsize=32768 .)

 This value is negotiated with the server.


 
 
    wsize=n

 
 The number of bytes NFS uses when writing files to an NFS server.


The default value is dependent on the kernel, currently 4096 bytes.


(However, throughput is improved greatly by asking for


  wsize=32768 .)

 This value is negotiated with the server.


 
 
    timeo=n

 
 The value in tenths of a second before sending the


first retransmission after an RPC timeout.


The default value depends on whether


  proto=udp

 or


  proto=tcp

 is in effect (see below).


The default value for UDP is 7 tenths of a second.


The default value for TCP is 60 seconds.


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.


 
 
    retrans=n

 
 The number of minor timeouts and retransmissions that must occur before


a major timeout occurs.  The default is 5 timeouts for


  proto=udp

 and 2 timeouts for


  proto=tcp .

 When a major timeout


occurs, 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 should


be 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 can


be 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 should


be 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 can


be cached before requesting fresh information from a server.


The default is 60 seconds.


 
 
    actimeo=n

 
 Using actimeo sets all of


  acregmin,

   acregmax,

   acdirmin,

 and


  acdirmax

 to the same value.


There is no default value.


 
 
    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.


 
 
    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.


 
 
    proto=n

 
 Mount the NFS filesystem using a specific network protocol


instead of the default UDP protocol.


Many NFS version 4 servers only support TCP.


Valid protocol types are


  udp

 and


  tcp .

 
 
 
    clientaddr=n

 
 On a multi-homed client, this


causes the client to use a specific callback address when


communicating with an NFS version 4 server.


This option is currently ignored.


 
 
    sec=mode

 
 Same as <3>sec=mode<1> for the nfs filesystem type (see above).


 
 
    bg

 
 If an 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.


 
 
    fg

 
 If the first NFS mount attempt times out, retry the mount


in the foreground.


This is the complement of the


  bg

 option, and also the default behavior.


 
 
    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.


 
 
    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 to


return EINTR to the calling program.  The default is to not


allow file operations to be interrupted.


 
 
    nocto

 
 Suppress the retrieval of new attributes when creating a file.


 
 
    noac

 
 Disable attribute caching, and force synchronous writes.


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.


All of the non-value options have corresponding nooption forms.


For example, nointr means don't allow file operations to be


interrupted.