Manual Pages  — STABLERESTART

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 There are records which indicate that a client successfully acquired state and records that indicate a client's state was revoked.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.