This message usually indicates that the bandwidth that is available for replication is less than optimal, causing a bottleneck on the primary. This does not cause any problems, other than reduced replication performance. If the current replication performance is acceptable, the messages can be disregarded.

As the message suggests, it is possible that the amount of memory available to Veritas Volume Replicator (VVR) is too low. You can check the current values by running vxtune and vxmemstat.

vol_max_nmpool_sz (NMCOM POOL SIZE): Specifies the maximum memory that will be used by VVR on a secondary to hold the write requests coming from the primary.
Default value is between 8192K and 16384KB
Permissible Value: 4096KB to 524288KB

vol_max_rdback_sz (READBACK POOL SIZE): Specifies the maximum memory that will be used by VVR, when write requests are being read back from the Replicator Log or from data volumes.
Default value is between 8192K and 16384KB
Permissible Value: 4096KB to 524288KB

vol_min_lowmem_sz (BASE MEMORY): Specifies the minimum threshold of available VVR memory needed to keep the write requests in memory on the primary replicated volume group (RVG) before sending it to secondary.
Default Value 1024KB
Permissible Value: 512KB to 10240KB

NOTE: The value of BASE MEMORY is usually not modified.

vol_rvio_maxpool_sz (MAX MEMORY): Specifies the maximum memory requested from the system by VVR for its use. This memory is shared between both SFW and VVR.
Default Value 32768KB
Permissible Value: 4096KB to 1048576KB

NOTE: In most cases, increasing NMCOM or READBACK to values higher than 16384KB (other than MAX MEMORY) is not recommended and may result in a shortage of non-paged pool memory on the server. If the "/3GB" switch is being used, values higher than 8192K for either NMCOM or READBACK are usually not recommended since the "/3GB" reduces the amount of non-paged pool memory available to drivers.

After changing the value of any of the tunables, the Veritas services should be restarted. Information on properly restarting the Veritas services can be found here: http://support.veritas.com/docs/288483