diff mbox

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

Message ID 20130910190721.2269.70727.stgit@seurat.1015granger.net (mailing list archive)
State New, archived
Headers show

Commit Message

Chuck Lever III Sept. 10, 2013, 7:26 p.m. UTC 
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---

This has been floating around for a while in my nfs-utils repo.
Now that migration support is getting merged upstream, I propose
this minor change to nfs(5).

Note that my pending migration patches currently allow migration
even if the "migration" option is not specified.  In this case,
standard state recovery will occur on the destination server (aka a
non-TSM migration) since the destination server can't match up a
client using the traditional clientid string with incoming migrated
state.

If we think this is dangerous to allow, then the client can be
changed to require the "migration" option to enable migration
support on NFSv4.0 mount points.

Non-TSM migration can still occur if the servers for some reason
fail to transfer open and lock state during a migration.

Comments...?

 utils/mount/nfs.man |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)


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diff mbox

Patch

diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
index 2a42b93..e93bd16 100644
--- a/utils/mount/nfs.man
+++ b/utils/mount/nfs.man
@@ -855,6 +855,26 @@  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 greater than zero,
+as these versions always use TSM-compatible client identification strings.
 .SH nfs4 FILE SYSTEM TYPE
 The
 .BR nfs4