On Tue, 2022-08-16 at 09:35 +1000, NeilBrown wrote: > > Currently the Linux NFS renews leases at 2/3 of the lease time > advised > by the server. > Some server vendors (Not Exactly Targeting Any Particular Party) > recommend very short lease times - as short a 5 seconds in fail-over > configurations. This means 1.7 seconds of jitter in any part of the > system can result in leases being lost - but it does achieve fast > fail-over. > > If we could configure a 5 second lease-renewal on the client, but > leave > a 60 second lease time on the server, then we could get the best of > both > worlds. Failover would happen quickly, but you would need a much > longer > load spike or network partition to cause the loss of leases. > > As v4.1 can end the grace period early once everyone checks in, a > large > grace period (which is needed for a large lease time) would rarely be > a > problem. > > So my thought is to add a mount option "lease-renew=5" for v4.1+ > mounts. > The clients then uses that number providing it is less than 2/3 of > the > server-declared lease time. > > What do people think of this? Is there a better solution, or a > problem > with this one? > > NeilBrown > I don't see how the NFS client can ever guarantee a 5 second lease renewal time, so as far as I'm concerned, this is not a problem we need to solve. -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
