No connectivity No centralized disk No centralized tape
Today, SAN islands are prevalent in large enterprises. This is because building large scalable fabrics has been difficult in the past:
• There has been a lack of affordable, standards-based, easy-to- implement WAN connectivity solutions.
• Scalability issues—low-port-count switches require lots of ISLs to build large meshes or core-edge configurations.
• Control traffic overhead and even CPU overhead can be problems on older switches when many switches are sharing the same fabric services.
• One configuration error or crashed process can take down the entire fabric. This is a reliability issue.
• Security issues arise when connecting large numbers of devices to a core fabric. Departments build their own SANs because they want to maintain control over their own applications.