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Connection Limits and Instance Sizes

Atlas sets the limits for concurrent incoming connections based on instance size:

Instance Size Maximum Number of Concurrent Incoming Connections
M0 100
M2 100
M5 100
M10 350
M20 700
M30 2000
M40 / M40 Low CPU * 4000
M50 / M50 Low CPU * 16000
M60 / M60 Low CPU * 32000
M80 Low CPU * 64000
M90 64000
M100 96000
M140 96000
M200 / M200 Low CPU * 128000
M300 128000
M400 Low CPU * 128000

* Low CPU instances are available with AWS clusters only.

Note

Atlas reserves a small portion of connections to each Atlas cluster for supporting Atlas services. Contact Atlas support for more information on Atlas reserved connections.