System Administration Guide, Volume 3


This daemon supports record-locking operations on NFS files. It sends locking requests from the client to the NFS server. On the NFS server, it starts local locking. The daemon is normally started without any options. You can use three options with this command (see the lockd(1M) man page).

The -g graceperiod option selects the number of seconds that the clients have to reclaim locks after a server reboot. During this time, the NFS server only processes reclaims of old locks. All other requests for service must wait until the grace period is over. This option affects the NFS server-side response, so it can be changed only on an NFS server. The default value for graceperiod is 45 seconds. Reducing this value means that NFS clients can resume operation more quickly after a server reboot, but a reduction increases the chances that a client might not be able to recover all its locks.

The -t timeout option selects the number of seconds to wait before retransmitting a lock request to the remote server. This option affects the NFS client-side service. The default value for timeout is 15 seconds. Decreasing the timeout value can improve response time for NFS clients on a noisy network, but it can cause additional server load by increasing the frequency of lock requests.

The nthreads option specifies the maximum number of concurrent threads that the server handles per connection. Base the value for nthreads on the load expected on the NFS server. The default value is 20. Because each NFS client using TCP uses a single connection with the NFS server, each TCP client is granted the ability to use up to 20 concurrent threads on the server. All NFS clients using UDP share a single connection with the NFS server. Under these conditions it might be necessary to increase the number of threads available for the UDP connection. A minimum calculation would be to allow two threads for each UDP client, but this is specific to the workload on the client, so two threads per client might not be sufficient. The disadvantage to using more threads is that when the threads are used, more memory is used on the NFS server, but if the threads are never used, increasing nthreads will have no effect.