A lot. As virtual server environments become more dependent on networked storage (NAS, iSCSI, SAN), the flexibility of being able to migrate VMs from host to host depends on storage access; although it would be nice, you can't have all servers access all storage. Typically, you'll want to stick with a single switch vendor and a single HBA vendor to decrease the chances that you will have incompatibility issues around drivers, microcode, and firmware. Once you have standards for storage, HBAs, and switches or directors, upgrades are less complex and predictable.
Dig Deeper on Virtual server backup and storage
Related Q&A from James E. Geis
It's possible to virtualize streaming video, but deployment depends on network, storage I/O, and bandwidth requirements of the virtual host, says an ... Continue Reading
Data deduplication options for virtualized servers might impact performance by creating data bottlenecks, according to an expert. Continue Reading
In a physical-to-virtual migration, getting a handle on your server and storage requirements as well as disaster recovery needs can significantly ... Continue Reading