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
