Cisco Systems Inc. is making its Fibre Channel SAN switches aware of the virtual machines attached to them through joint development with VMware Inc. "The virtual machine has become the atomic unit of the data center," said Rajeev Bhardwaj, director of product management. The update to Cisco's NX-OS switch operating system means that VMware ESX Servers connected through MDS 9000 fabric switches using NPIV can have separate logins and separate VSANs. ESX Servers can also be given access to multiple VSANs on an individual level, rather than being grouped by physical host. The update to NX-OS allows quality of service according to virtual machine. The update also enables security attributes, such as authentication and access protocols, to follow the virtual machine if it's moved across networks using VMotion. Furthermore, storage administrators don't need to reconfigure or redesign the SAN fabric when moving virtual servers; they can create server pools consisting of virtual partitions of infrastructure offering different levels of service.