nfs(5): Document the "migration" mount option

Support for NFSv4 migration was merged in 3.13.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
index 67031b5..89a5963 100644
--- a/utils/mount/nfs.man
+++ b/utils/mount/nfs.man
@@ -856,6 +856,26 @@ In the presence of multiple client network interfaces,
 special routing policies,
 or atypical network topologies,
 the exact address to use for callbacks may be nontrivial to determine.
+.TP 1.5i
+.BR migration " / " nomigration
+Selects whether the client uses an identification string that is compatible
+with NFSv4 Transparent State Migration (TSM).
+If the mounted server supports NFSv4 migration with TSM, specify the
+.B migration
+option.
+.IP
+Some server features misbehave in the face of a migration-compatible
+identification string.
+The
+.B nomigration
+option retains the use of a traditional client indentification string
+which is compatible with legacy NFS servers.
+This is also the behavior if neither option is specified.
+A client's open and lock state cannot be migrated transparently
+when it identifies itself via a traditional identification string.
+.IP
+This mount option has no effect with NFSv4 minor versions newer than zero,
+which always use TSM-compatible client identification strings.
 .SH nfs4 FILE SYSTEM TYPE
 The
 .BR nfs4