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Controlling the network bandwidth used for replication

VVR uses the network to replicate data from the Primary to the Secondary. The Bandwidth Throttling feature enables you to control the maximum network bandwidth to be used by VVR for replication. Bandwidth Throttling controls the rate at which data is sent from the Primary to the Secondary; it does not limit the rate at which the network acknowledgements are sent from the Secondary to the Primary.

You might want to control the bandwidth used by VVR depending on factors such as whether the available network connection is to be used by other applications or exclusively for VVR, the network costs, and network usage over time. For example, if the network is used for purposes other than replication, you might have to control the network bandwidth used by VVR.

Decide on the bandwidth limit for VVR depending on the bandwidth required for VVR, and the bandwidth required for other purposes. For information on how to decide the bandwidth limit to specify for VVR, refer to the Veritas Volume Replicator Planning and Tuning Guide, and the Veritas Volume Replicator Advisor User's Guide.

VVR enables you to change the network bandwidth used for replication to a Secondary even when replication is in progress. It is not necessary to pause replication before you change the bandwidth limit for a Secondary or for an RDS.

Use the vrstat command to determine the network bandwidth currently used by VVR. For instructions, see Determining the network bandwidth being used by VVR.

Use the bandwidth_limit attribute of the vradmin set command to set the limit on the network bandwidth used to replicate from the Primary to the Secondary. For example, if bandwidth_limit is set to 30 mbps, VVR uses 30 mbps for replication. If bandwidth_limit is set to none, then VVR uses the available network bandwidth. The default value is none.

You can also control the network bandwidth used by VVR when synchronizing volumes, which are not part of an RDS; use the bandwidth_limit attribute of the vradmin syncvol command to specify the limit.


  Note   This value of bandwidth_limit specified in the vradmin syncvol command is in addition to the bandwidth limit set for replication.


For example, if bandwidth_limit is set to 30 mbps for replication between a Primary and Secondary in an RDS, and the bandwidth limit to be used when synchronizing volumes that are not part of an RDS using the vradmin syncvol command is specified as 10 mbps, then together VVR will use a maximum of 40 mbps.