1.\" Copyright (c) 2009 Rick Macklem, University of Guelph 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd April 10, 2011 28.Dt STABLERESTART 5 29.Os 30.Sh NAME 31.Nm nfs-stablerestart 32.Nd restart information for the 33.Tn NFSv4 34server 35.Sh SYNOPSIS 36.Nm nfs-stablerestart 37.Sh DESCRIPTION 38The 39.Nm 40file holds information that allows the 41.Tn NFSv4 42server to restart without always returning the NFSERR_NOGRACE error, as described in the 43.Tn NFSv4 44server specification; see 45.%T "Network File System (NFS) Version 4 Protocol RFC 3530, Section 8.6.3" . 46.Pp 47The first record in the file, as defined by struct nfsf_rec in 48/usr/include/fs/nfs/nfsrvstate.h, holds the lease duration of the 49last incarnation of the server and the number of boot times that follows. 50Following this are the number of previous boot times listed in the 51first record. 52The lease duration is used to set the grace period. 53The boot times 54are used to avoid the unlikely occurrence of a boot time being reused, 55due to a TOD clock going backwards. 56This record and the previous boot times with this boot time 57added is re-written at the end of the grace period. 58.Pp 59The rest of the file are appended records, as defined by 60struct nfst_rec in /usr/include/fs/nfs/nfsrvstate.h and are used represent one of two things. 61There are records which indicate that a 62client successfully acquired state and records that indicate a client's state was revoked. 63State revoke records indicate that state information 64for a client was discarded, due to lease expiry and an otherwise 65conflicting open or lock request being made by a different client. 66These records can be used to determine if clients might have done either of the 67edge conditions. 68.Pp 69If a client might have done either edge condition or this file is 70empty or corrupted, the server returns NFSERR_NOGRACE for any reclaim 71request from the client. 72.Pp 73For correct operation of the server, it must be ensured that the file 74is written to stable storage by the time a write op with IO_SYNC specified has returned. 75This might require hardware level caching to be disabled for 76a local disk drive that holds the file, or similar. 77.Sh FILES 78.Bl -tag -width /var/db/nfs-stablerestart.bak -compact 79.It Pa /var/db/nfs-stablerestart 80NFSv4 stable restart file 81.It Pa /var/db/nfs-stablerestart.bak 82backup copy of the file 83.El 84.Sh SEE ALSO 85.Xr nfsv4 4 , 86.Xr nfsd 8 87.Sh BUGS 88If the file is empty, the NFSv4 server has no choice but to return 89NFSERR_NOGRACE for all reclaim requests. 90Although correct, this is a highly undesirable occurrence, so the file should not be lost if 91at all possible. 92The backup copy of the file is maintained and used by the 93.Xr nfsd 8 94to minimize the risk of this occurring. 95To move the file, you must edit the nfsd sources and recompile it. 96This was done to discourage accidental relocation of the file. 97