STABLERESTART(5)					      BSD File Formats Manual						  STABLERESTART(5)

NAME

     nfs-stablerestart -- restart information for the NFSv4 server

SYNOPSIS

     nfs-stablerestart

DESCRIPTION

     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 incar-
     nation 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 There are records which indicate that a client successfully acquired state and records that indicate a client's state was
     revoked.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 speci-
     fied has returned. This might require hardware level caching to be disabled for a local disk drive that holds the file, or similar.

FILES

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

SEE ALSO

     nfsv4(4), nfsd(8)

BUGS

     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 discour-
     age accidental relocation of the file.

BSD
								  April 10, 2011							       BSD