How is a SAN different from DAS and NAS?
DAS (or Direct Attached Storage) devices are storage devices that are directly connected to the servers. Servers connect to these devices using high speed interconnects such as SCSI (Small Computer System Interface). The issue with DAS is that the storage utilization is low (on the average 50%) and space cannot be pooled, making management and maintenance difficult. NAS (or Network Attached Storage) device is a server that is dedicated to file sharing. It allows hard disk storage space to be added to a network without having to bring down these servers and allow the servers and workstations on the network to access this storage at a file level. There are two issues with NAS that SAN overcomes. First, there are applications such as databases that need a “block level” access to storage as opposed to a file level access, and second that the increased network traffic from servers to storage can cause congestion on local network. SAN allows a block level access to storage and since it has i
