Controls the number of TCP connections that the NFS client uses when communicating with each NFS server. The kernel RPC is constructed so that it can multiplex RPCs over a single connection. However, multiple connections can be used, if preferred.
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In general, one connection is sufficient to achieve full network bandwidth. However, if TCP cannot utilize the bandwidth offered by the network in a single stream, then multiple connections might increase the throughput between the client and the server.
Increasing the number of connections doesn't come without consequences. Increasing the number of connections also increases kernel resource usage needed to keep track of each connection.