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.Dd April 10, 2011 26.Dt STABLERESTART 5 27.Os 28.Sh NAME 29.Nm nfs-stablerestart 30.Nd restart information for the 31.Tn NFSv4 32server 33.Sh SYNOPSIS 34.Nm nfs-stablerestart 35.Sh DESCRIPTION 36The 37.Nm 38file holds information that allows the 39.Tn NFSv4 40server to restart without always returning the NFSERR_NOGRACE error, as described in the 41.Tn NFSv4 42server specification; see 43.%T "Network File System (NFS) Version 4 Protocol RFC 3530, Section 8.6.3" . 44.Pp 45The first record in the file, as defined by struct nfsf_rec in 46/usr/include/fs/nfs/nfsrvstate.h, holds the lease duration of the 47last incarnation of the server and the number of boot times that follows. 48Following this are the number of previous boot times listed in the 49first record. 50The lease duration is used to set the grace period. 51The boot times 52are used to avoid the unlikely occurrence of a boot time being reused, 53due to a TOD clock going backwards. 54This record and the previous boot times with this boot time 55added is re-written at the end of the grace period. 56.Pp 57The rest of the file are appended records, as defined by 58struct nfst_rec in /usr/include/fs/nfs/nfsrvstate.h and are used represent one of two things. 59There are records which indicate that a 60client successfully acquired state and records that indicate a client's state was revoked. 61State revoke records indicate that state information 62for a client was discarded, due to lease expiry and an otherwise 63conflicting open or lock request being made by a different client. 64These records can be used to determine if clients might have done either of the 65edge conditions. 66.Pp 67If a client might have done either edge condition or this file is 68empty or corrupted, the server returns NFSERR_NOGRACE for any reclaim 69request from the client. 70.Pp 71For correct operation of the server, it must be ensured that the file 72is written to stable storage by the time a write op with IO_SYNC specified has returned. 73This might require hardware level caching to be disabled for 74a local disk drive that holds the file, or similar. 75.Sh FILES 76.Bl -tag -width /var/db/nfs-stablerestart.bak -compact 77.It Pa /var/db/nfs-stablerestart 78NFSv4 stable restart file 79.It Pa /var/db/nfs-stablerestart.bak 80backup copy of the file 81.El 82.Sh SEE ALSO 83.Xr nfsv4 4 , 84.Xr nfsd 8 85.Sh BUGS 86If the file is empty, the NFSv4 server has no choice but to return 87NFSERR_NOGRACE for all reclaim requests. 88Although correct, this is a highly undesirable occurrence, so the file should not be lost if 89at all possible. 90The backup copy of the file is maintained and used by the 91.Xr nfsd 8 92to minimize the risk of this occurring. 93To move the file, you must edit the nfsd sources and recompile it. 94This was done to discourage accidental relocation of the file. 95