for 12 hosts the difference between the total migration time of gmgd and gmld can be attributed to the overhead associated with gmgd for performing deduplication across the hosts while the migration is in progress it queries with the deduplication server to read or update the status of deduplicated pages such requests need to be sent frequently to perform effective deduplication 2 busy vms table i shows that dbench equally increases the total migration time of all the vm migration techniques as compared to their total migration time with idle vms however a slight reduction in the total migration time is observed with an increasing number of hosts with a lower number of hosts and therefore a lower number of vms the incoming 1 gbps ethernet link to the network attached storage server might remain unsaturated and therefore each dbench instance can perform i o at a faster rate compared to a scenario with more vms where the vms must contend for the available bandwidth the faster i o rate results in higher page dirtying rate resulting in more data being transferred during vms 39 migration fig6 shows that increasing the number of hosts does not have a significant impact on the downtimes for all three schemes this is because each vm 39 s downtime is initiated independently of other vms however the downtime for oc is slightly higher in the range of 250 ms to 280 ms with the three rack testbed used in the above experiments the core links remain uncongested due to limited number of hosts in each source rack to evaluate the effect of congestion at core links for the.