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STABLERESTART(5)	    BSD	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 de-
     scribed 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/in-
     clude/fs/nfs/nfsrvstate.h,	holds the lease	duration of the	last incarna-
     tion 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 ac-
     quired state and records that indicate a client's state was revoked.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	NF-
     SERR_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.

BSD				April 10, 2011				   BSD


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