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NFS Mount Throughput Calculator

Work out nfs mount throughput instantly with clear inputs, formula shown and shareable results.

About NFS Mount Throughput Calculator

NFS throughput is limited by the same bandwidth-delay logic as TCP: outstanding requests multiplied by rsize divided by round-trip time. Small rsize values or too few outstanding requests leave a fast network idle waiting for round trips, which is why raising rsize and wsize to 1 MB and increasing the RPC slot count matter so much on higher-latency links.

Formula

NFS throughput

latency limit = rsize x outstanding requests x 8 / RTT; effective = min(0.9 x network rate, latency limit)

Worked example

With the default values below, NFS Mount Throughput Calculator returns Effective NFS throughput of 900.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Network bandwidthminimum 0.001 Mbps
1,000 Mbps
rsize / wsizeaccepts 4–1,024 KB
1,024 KB
Round-trip time to the serverminimum 0.001 ms
0.4 ms
Outstanding requestsaccepts 1–256
16

Results

Effective NFS throughput
900.0 Mbps
Ceiling from latency and concurrency
335,544.3 Mbps
Ceiling from network bandwidth
900.0 Mbps
Binding constraint
Network bandwidth

Step by step

  1. 1Values used
  2. 2NFS throughput
  3. 3Effective NFS throughput= 900.0 Mbps
  4. 4Ceiling from latency and concurrency= 335,544.3 Mbps
  5. 5Ceiling from network bandwidth= 900.0 Mbps
  6. 6Binding constraint= Network bandwidth

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Should I use NFS over UDP?

No. TCP handles retransmission and congestion properly, and UDP support is deprecated. NFSv4 over TCP is the correct choice.

Why is my NFS slower than the network?

Usually too few outstanding RPCs or a small rsize. Also check for synchronous writes, which force a round trip per operation and destroy throughput.

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