How to increase the TCP receive window buffer size for Inter-Cluster and IntraCluster Volume SnapMirror
- ONTAP 9
- Clustered Data ONTAP 8
Inter-Cluster and IntraCluster SnapMirror uses the network service named
ctlopcpservice has a tunable TCP receive buffer window for Inter-Cluster and IntraCluster connections.
- The Inter-Cluster TCP receive buffer window defaults to 2 MB, the IntraCluster TCP receive buffer window defaults to 256 KB.
- The TCP receive buffer windows can be increased up to 7 MB, and can be decreased to 256 KB.
- Increasing the Inter-Cluster TCP receive buffer window can increase the effective throughput when working with high-capacity WAN connections.
- However, this may not be necessary due to the increased number of active TCP streams used for replication.
- For more information, see Section 2.4 "Network Connections for Inter-Cluster SnapMirror" in TR-4015.
- Inter-Cluster TCP receives buffer windows auto-tune by default.
- These start at 64KB per TCP stream and grow to a maximum of the configured value (default 2MB) to accommodate InterCluster replications.
- Once grown, the receive buffer window does not shrink as long as the TCP stream remains open.