Storage Area Networks can be Fibre Channel-based (FC) or IP-based (iSCSI). For Fibre Channel SANs a separate network is required and consists of specialized hardware (HBAs for hosts that require connectivity to the SAN and SAN switches). iSCSI SANs can utilize pre-existing networks but are best designed as dedicated IP networks to avoid contention between storage and client/server traffic.
Regardless of whether the SAN is Fibre Channel or iSCSI-based, SANs provide only for the consolidation of the physical storage resources and in every other way resemble a Direct Attach Storage (DAS) environment. Each server still owns its respective file system and data is still shared by the general-purpose server and must be backed up on a server-by-server basis.
SANs are beneficial when applications require the speed of direct block translation and are typically implemented for large-scale database applications.
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