20d0a5e544
This includes the addition of a new flag "-4" that will force use of the experimental server with nfsv4 support in it. This commit also adds two new man pages to the repository that are NFSv4 specific. One describes the file used by the server to restart nfsv4 services safely. The other is a brief overview of nfsv4 and its setup. Reviewed by: dfr Approved by: kib (mentor)
94 lines
4.0 KiB
Groff
94 lines
4.0 KiB
Groff
.\" Copyright (c) 2009 Rick Macklem, University of Guelph
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd Sept 7, 2007
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.Dt STABLERESTART 5
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.Os
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.Sh NAME
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.Nm nfs-stablerestart
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.Nd handles restart edge conditions for the
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.Tn NFS
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V4 server
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.Sh SYNOPSIS
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.Nm nfs-stablerestart
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.Sh DESCRIPTION
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The
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.Nm
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file holds information that allows the
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.Tn NFS
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V4 server to restart without always returning the NFSERR_NOGRACE error, as described in the
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.Tn NFS V4
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server specification; see
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.%T "Network File System (NFS) Version 4 Protocol \\*(tNRFC\\*(sP 3530, Section 8.6.3" .
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.Pp
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The first record in the file, as defined by struct nfsf_rec in
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/usr/include/fs/nfs/nfsrvstate.h, holds the lease duration of the
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last incarnation of the server and the number of boot times that follows.
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Following this are the number of previous boot times listed in the
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first record.
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The lease duration is used to set the Grace Period.
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The boot times
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are used to avoid the unlikely occurrence of a boot time being reused,
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due to a TOD clock going backwards. This record and the previous boot times with this boot time added is re-written at the
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end of the Grace Period.
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.Pp
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The rest of the file are appended records, as defined by
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struct nfst_rec in /usr/include/fs/nfs/nfsrvstate.h and are used
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represent one of two things. There are records which indicate that a
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client successfully aquired state and records that indicate a client's state was revoked.
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State revoke records indicate that state information
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for a client was discarded, due to lease expiry and an otherwise
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conflicting open or lock request being made by a different client.
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These records can be used
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to determine if clients might have done either of the
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edge conditions.
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.Pp
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If a client might have done either edge condition or this file is
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empty or corrupted, the server returns NFSERR_NOGRACE for any reclaim
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request from the client.
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.Pp
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For correct operation of the server, it must be ensured that the file
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is written to stable storage by the time a write op with IO_SYNC specified
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has returned. This might require hardware level caching to be disabled for
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a local disk drive that holds the file, or similar.
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.Sh FILES
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.Bl -tag -width /var/db/nfs-stablerestart -compact
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.It Pa /var/db/nfs-stablerestart
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NFS V4 stable restart file
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.El
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.Sh SEE ALSO
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.Xr nfsv4 4
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.Xr nfsd 8
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.Sh BUGS
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If the file is empty, the NFS V4 server has no choice but to return
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NFSERR_NOGRACE for all Reclaim requests. Although correct, this is
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a highly undesirable occurrence, so the file should not be lost if
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at all possible. Nfsd will not create the file if it does not
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exist and will simply log a failure to start, in the hopes that the
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file can be recovered from a backup. To move the file, you must edit
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the nfsd sources and recompile it. This was done to discourage
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accidental relocation of the file.
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