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Diffstat (limited to 'usr.sbin/nfsd/stablerestart.5')
| -rw-r--r-- | usr.sbin/nfsd/stablerestart.5 | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/usr.sbin/nfsd/stablerestart.5 b/usr.sbin/nfsd/stablerestart.5 new file mode 100644 index 0000000..c469835 --- /dev/null +++ b/usr.sbin/nfsd/stablerestart.5 @@ -0,0 +1,93 @@ +.\" Copyright (c) 2009 Rick Macklem, University of Guelph +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd Sept 7, 2007 +.Dt STABLERESTART 5 +.Os +.Sh NAME +.Nm nfs-stablerestart +.Nd handles restart edge conditions for the +.Tn NFS +V4 server +.Sh SYNOPSIS +.Nm nfs-stablerestart +.Sh DESCRIPTION +The +.Nm +file holds information that allows the +.Tn NFS +V4 server to restart without always returning the NFSERR_NOGRACE error, as described in the +.Tn NFS V4 +server specification; see +.%T "Network File System (NFS) Version 4 Protocol \\*(tNRFC\\*(sP 3530, Section 8.6.3" . +.Pp +The first record in the file, as defined by struct nfsf_rec in +/usr/include/fs/nfs/nfsrvstate.h, holds the lease duration of the +last incarnation of the server and the number of boot times that follows. +Following this are the number of previous boot times listed in the +first record. +The lease duration is used to set the Grace Period. +The boot times +are used to avoid the unlikely occurrence of a boot time being reused, +due to a TOD clock going backwards. This record and the previous boot times with this boot time added is re-written at the +end of the Grace Period. +.Pp +The rest of the file are appended records, as defined by +struct nfst_rec in /usr/include/fs/nfs/nfsrvstate.h and are used +represent one of two things. There are records which indicate that a +client successfully aquired state and records that indicate a client's state was revoked. +State revoke records indicate that state information +for a client was discarded, due to lease expiry and an otherwise +conflicting open or lock request being made by a different client. +These records can be used +to determine if clients might have done either of the +edge conditions. +.Pp +If a client might have done either edge condition or this file is +empty or corrupted, the server returns NFSERR_NOGRACE for any reclaim +request from the client. +.Pp +For correct operation of the server, it must be ensured that the file +is written to stable storage by the time a write op with IO_SYNC specified +has returned. This might require hardware level caching to be disabled for +a local disk drive that holds the file, or similar. +.Sh FILES +.Bl -tag -width /var/db/nfs-stablerestart -compact +.It Pa /var/db/nfs-stablerestart +NFS V4 stable restart file +.El +.Sh SEE ALSO +.Xr nfsv4 4 +.Xr nfsd 8 +.Sh BUGS +If the file is empty, the NFS V4 server has no choice but to return +NFSERR_NOGRACE for all Reclaim requests. Although correct, this is +a highly undesirable occurrence, so the file should not be lost if +at all possible. Nfsd will not create the file if it does not +exist and will simply log a failure to start, in the hopes that the +file can be recovered from a backup. To move the file, you must edit +the nfsd sources and recompile it. This was done to discourage +accidental relocation of the file. |
