2.4. Turn off TCP Segmentation


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2.4. Turn off TCP Segmentation

Under certain conditions, the use of TCP segmentation offload (TSO) and generic receive offload (GRO) can cause nodes to randomly drop out of a cluster. The symptoms of this problem are that nodes timeout — that is, the rest of the cluster thinks they have failed — although the node is still running and no other network issues (such as a network partition) are the cause.

Disabling TSO and GRO is recommended for any VoltDB clusters that experience such instability. The commands to disable offloading are the following, where N is replaced by the number of the ethernet card:

ethtool -K ethN tso off
ethtool -K ethN gro off

Note that these commands disable offloading temporarily. You must issue these commands every time the node reboots or, preferably, put them in a startup configuration file.