Command Section
STABLERESTART(5)          FreeBSD File Formats Manual         STABLERESTART(5)

     nfs-stablerestart - restart information for the NFSv4 server


     The nfs-stablerestart file holds information that allows the NFSv4 server
     to restart without always returning the NFSERR_NOGRACE error, as
     described in the NFSv4 server specification; see Network File System
     (NFS) Version 4 Protocol RFC 3530, Section 8.6.3.

     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.

     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
     acquired state and records that indicate a client's state was revoked.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.

     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.

     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.

     /var/db/nfs-stablerestart      NFSv4 stable restart file
     /var/db/nfs-stablerestart.bak  backup copy of the file

     nfsv4(4), nfsd(8)

     If the file is empty, the NFSv4 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. The backup copy of the file is maintained and used by the
     nfsd(8) to minimize the risk of this occurring.  To move the file, you
     must edit the nfsd sources and recompile it. This was done to discourage
     accidental relocation of the file.

FreeBSD 11.1-RELEASE-p4         April 10, 2011         FreeBSD 11.1-RELEASE-p4
Command Section