Resolution:
According to  (http://wiki.tangosol.com/pages/viewpage.action?pageId=16705), this warning will be issued if the OS allocates a smaller socket buffer than what Coherence has requested.

Though it is safe to operate with the smaller buffers it is recommended that you configure your OS to allow for larger buffers. To help resolve the errors/warnings, please refer to the Datagram Test (Tuning) at: http://wiki.tangosol.com/display/COH33UG/Datagram+Test#DatagramTest-DatagramTestTuning.

OS related settings for this error that the Unix Admin can review are listed at the following URL:
http://wiki.tangosol.com/display/COH32UG/Performance+Tuning#PerformanceTuning-OSTuning

For eg.
---------
On AIX execute (as root):

no -o rfc1323=1
no -o sb_max=4194304
no -o udp_recvspace=4194304
no -o udp_sendspace=65536

Note that AIX only supports specifying receive buffer sizes of 1MB, 4MB, and 8MB. Additionally there is an issue with IBM's 1.4.2, and 1.5 JVMs which may prevent them from allocating socket buffers larger then 64K. This issue has been addressed in IBM's 1.4.2 SR7 SDK and 1.5 SR3 SDK.