Recent studies on companies’ data-centers show that a VM consume an average of 4 GB of Memory and 128 GB of storage. Thus, it will take a minimum of 17.5 minutes (resp. 1.75 minutes) with a 1 Gb/s (resp. 10 Gb/s) network to realize a complete VM migration. Moreover, a classical consolidation ratio in virtualized data centers is 50 VMs per server. According to the approach that we are considering in EPOC (VOVO Policy), our data center needs to be able to migrate all the VMs running on a server (7.5 TB), whenever the hypervisor requests to turn this server off in order to save power. Having one optical port per rack means that its bandwidth might be shared by the servers located in this rack. Then, is this bandwidth enough to migrate all the VMs in one server? Using 10 Gb/s this operation takes around 2 hours. However, if we consider an example, 32 servers per rack, the same operation would take about 53 hours, since now the bandwidth is being shared by the 32 servers. Consequently, increasing the bit rate of the interconnection network becomes a must. 

To overcome the aforementioned problem, classical dynamic consolidation system uses live migration with a Storage Area Network (SAN). In this case, the VM storage is shared between all servers and live mi- gration is limited to transfer VMs memory. Nevertheless, adding a SAN impacts on the global DC en- ergy consumption. EpoCloud proposes to suppress the SAN, which is a dedicated network providing access to consolidated data storage. But Turning off a server involves transferring 7.5 TB on average...