Subject: [nfsv4] Lease time and Grace period

From: Frank S Filz <[email-masked]>
Date: Tue, 7 May 2013 10:57:31 -0700

RFC 3530 only indicates that grace period SHOULD NOT be less than lease
period. Is there any guidance? Do clients renew more frequently (say 1/2
lease period) such that grace period being the same as lease period should
generally be sufficient?

Thanks

Frank

---

From: Rick Macklem <[email-masked]>
Date: Tue, 7 May 2013 20:10:11 -0400 (EDT)

Frank S. Filz wrote:
> RFC 3530 only indicates that grace period SHOULD NOT be less than
> lease period. Is there any guidance? Do clients renew more frequently
> (say 1/2 lease period) such that grace period being the same as lease
> period should generally be sufficient?
> 
Well, I'd say yes to the "clients renew more frequently than the lease,
so they see the NFS4ERR_STALECLIENTID or NFS4ERR_STALESTATEID before
a lease duration is up, is true".

However, back when I did some recovery testing using several clients
with many locks, I did find that they might not all complete recovery
before the original grace duration was done.
What I did was add code that "extends grace" so long as client(s) were
still sending reclaim Ops (Lock with reclaim==true or Open with CLAIM_PREVIOUS)
so that the FreeBSD server doesn't end grace until it has not seen any
more reclaim ops for some time (I think it's no more reclaims for a lease
duration, but the code isn't in front of me).

They fixed this in 4.1 by having clients send RECLAIM_COMPLETE when they
are done doing reclaims.

rick

> Thanks
> 
> Frank
> 
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