ARP not learning properly while cluster failover

[jeraldsimon84]

I have a cisco6500 serious switch that one port (portfast enabled) hold a  server .This server has sort of a Cluster configured for high availability .

During primary server failure the failover server acquires the cluster IP address (ie virtual IP).

Cluster IP 192.168.10.1

Primary server =192.168.10.2  Failover server =192.168.10.3

when failover happen , i am unable to learn arp. need to reboot the server for arp . After reboot i am getting different mac address(secondary) with cluster IP.

query:-normal clustering how mac address generating(means logicaly any mac address will be created or LAN card mac address)? 

how can check the server is generating gratuitous arp ?

how can avoid this issue ?

Note:-

Cisco ARP time out :4 hrs

Cisco Mac- address time out : 300 sec