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32 .Nd NFS Version 4 Protocol
34 experimental client and server with NFSv4 support
36 The experimental nfs client and server provides support for the
39 .%T "Network File System (NFS) Version 4 Protocol \\*(tNRFC\\*(sP 3530" .
40 The protocol is somewhat similar to NFS Version 3, but differs in significant
42 It uses a single Compound RPC that concatenates operations to-gether.
43 Each of these operations are similar to the RPCs of NFS Version 3.
44 The operations in the compound are performed in order, until one of
45 them fails (returns an error) and then the RPC terminates at that point.
48 integrated locking support, which implies that the server is no longer
52 server remains in recovery mode for a Grace period (always greater than the
53 lease duration the server uses) after a reboot.
54 During this Grace period, clients may recover state but not perform other
55 open/lock state changing operations.
56 To provide for correct recovery semantics, a small file described by
58 is used by the server during the recovery phase.
59 If this file is missing or empty, there is a backup copy maintained by
61 that will be used. If either file is missing, they will be
64 If both the file and the backup copy are empty,
65 it will result in the server starting without providing a grace period
67 Note that recovery only occurs when the server
68 machine is rebooted, not when the
72 It provides several optional features not in NFS Version 3:
74 .Bd -literal -offset indent -compact
76 - Referrals, which redirect subtrees to other servers
78 - Delegations, which allow a client to operate on a file locally
83 protocol does not use a separate mount protocol and assumes that the
84 server provides a single file system tree structure, rooted at the point
85 in the local file system tree specified by one or more
87 .Bd -literal -offset indent -compact
88 V4: <rootdir> [-sec=secflavors] [host(s) or net]
99 allows a limited subset of operations to be performed on non-exported subtrees
100 of the local file system, so that traversal of the tree to the exported
101 subtrees is possible.
102 As such, the ``<rootdir>'' can be in a non-exported file system.
104 the entire tree that is rooted at that point must be in local file systems
105 that are of types that can be NFS exported.
108 file system is rooted at ``<rootdir>'', setting this to anything other
109 than ``/'' will result in clients being required to use different mount
112 than for NFS Version 2 or 3.
113 Unlike NFS Version 2 and 3, Version 4 allows a client mount to span across
114 multiple server file systems, although not all clients are capable of doing
118 uses names for users and groups instead of numbers.
122 .Bd -literal -offset indent -compact
126 where ``<dns.domain>'' is not the same as the DNS domain used
127 for host name lookups, but is usually set to the same string.
128 Most systems set this ``<dns.domain>''
129 to the domain name part of the machine's
132 However, this can normally be overridden by a command line
133 option or configuration file for the daemon used to do the name<->number
135 On FreeBSD, the mapping daemon is called
137 and has a command line option that overrides the domain component of the
141 either client or server, this daemon must be running.
142 If this ``<dns.domain>'' is not set correctly or the daemon is not running, ``ls -l'' will typically
143 report a lot of ``nobody'' and ``nogroup'' ownerships.
145 Although uid/gid numbers are no longer used in the
147 protocol, they will still be in the RPC authentication fields when running
148 using AUTH_SYS (sec=sys), which is the default.
149 As such, in this case both the user/group name and number spaces must
150 be consistent between the client and server.
154 with RPCSEC_GSS (sec=krb5, krb5i, krb5p), only names and KerberosV tickets
158 To set up the experimental nfs server that supports
160 you will need to either build a kernel with:
162 .Bd -literal -offset indent -compact
166 .Bd -literal -offset indent -compact
174 with the ``-e'' option to force use of the experimental server.
177 daemon must also be running.
180 .Bd -literal -offset indent -compact
181 nfs_server_enable="YES"
182 nfsv4_server_enable="YES"
183 nfsuserd_enable="YES"
189 You will also need to add at least one ``V4:'' line to the
195 If the file systems you are exporting are only being accessed via
197 there are a couple of
199 variables that you can change, which might improve performance.
201 .It Cm vfs.newnfs.issue_delegations
202 when set non-zero, allows the server to issue Open Delegations to
204 These delegations permit the client to manipulate the file
205 locally on the client.
206 Unfortunately, at this time, client use of
207 delegations is limited, so performance gains may not be observed.
208 This can only be enabled when the file systems being exported to
210 clients are not being accessed locally on the server and, if being
211 accessed via NFS Version 2 or 3 clients, these clients cannot be
213 .It Cm vfs.newnfs.enable_locallocks
214 can be set to 0 to disable acquisition of local byte range locks.
215 Disabling local locking can only be done if neither local accesses
216 to the exported file systems nor the NLM is operating on them.
219 Note that Samba server access would be considered ``local access'' for the above
222 To build a kernel with the experimental
226 .Bd -literal -offset indent -compact
230 must be specified in the kernel's
237 mount, specify the ``nfsv4'' option on the
240 This will force use of the experimental client plus set ``tcp'' and
245 must be running, as above.
248 server that is being mounted on supports delegations, you can start the
250 daemon to handle client side callbacks.
253 .Bd -literal -offset indent -compact
254 nfsuserd_enable="YES"
261 Without a functioning callback path, a server will never issue Delegations
264 By default, the callback address will be set to the IP address acquired via
265 rtalloc() in the kernel and port# 7745.
266 To override the default port#, a command line option for
270 To get callbacks to work when behind a NAT gateway, a port for the callback
271 service will need to be set up on the NAT gateway and then the address
272 of the NAT gateway (host IP plus port#) will need to be set by assigning the
274 variable vfs.newnfs.callback_addr to a string of the form:
278 where the first 4 Ns are the host IP address and the last two are the
279 port# in network byte order (all decimal #s in the range 0-255).
281 To build a kernel with the experimental
283 client linked into it, the option
285 .Bd -literal -offset indent -compact
289 must be specified in the kernel's
293 Options can be specified for the
297 daemons at boot time via the ``nfsuserd_flags'' and ``nfscbd_flags''
301 .Bl -tag -width /var/db/nfs-stablerestart.bak -compact
302 .It Pa /var/db/nfs-stablerestart
303 NFS V4 stable restart file
304 .It Pa /var/db/nfs-stablerestart.bak
305 backup copy of the file
316 At this time, there is no recall of delegations for local file system
318 As such, delegations should only be enabled for file systems
319 that are being used solely as NFS export volumes and are not being accessed
320 via local system calls nor services such as Samba.