Maximizing SFTP Performance

SFTP requires several request-and-response exchanges during a transfer, so network latency and client settings can have a large effect on throughput. Tune the client settings below, then measure performance with representative files.

Maximize the Buffer Size (Data Chunk Size) in Your SFTP Client

Many SFTP clients send data in 32-kilobyte chunks.

Test a larger value, beginning with 128 kilobytes. Increase it gradually and compare results; the best value depends on the client and network path.

With the command-line sftp client, use the -B option:

sftp -B 128000 [e-mail]

For any other client, look for settings related to buffer size or data chunk size and raise them.

Use Many Parallel Connections

When transferring many files, configure 10 to 25 simultaneous connections or the maximum supported by the client.

In FileZilla, open Edit > Settings > Transfers and increase the Maximum simultaneous transfers setting to 10.

In Cyberduck, open Edit > Preferences > Transfers and set Transfer Files to Open multiple connections. Then open Window > Transfers and increase the counter in the lower-right corner.

Increasing the number of simultaneous connections helps when uploading multiple files at the same time but has no effect when uploading a single file.

Minimize Network Latency

Network latency is the round-trip delay between sending data and receiving a response. Higher latency can be caused by:

• The physical limitations of the network connection

• Other traffic consuming the connection's capacity

• The network distance between the client and appliance

• Network tools or policies that regulate bandwidth

Network latency has a large impact on SFTP performance. Use the shortest practical network path and a stable wired connection when available.