SAN vs NAS vs DAS
From DAS to NAS to SANs: the Evolution of Storage Configurations
A refresher course on the different configurations for storage can be useful. In the old days, things were simpler, though they didn’t seem so at the time. There was just direct-attached storage or DAS. In other words, hard drives are connected directly to computers in a one-to-one relationship¬—one drive serving one CPU. The advantages of DAS include simplicity and, without a network in-between for reads and writes, speed.
The advent of workgroups and collaborations, however, required file sharing. Handing colleagues floppies with files on them was inefficient and impractical. To the rescue came network-attached storage, or NAS. Users on a network could access files, data, and applications residing on servers. NAS introduced a paradigm of one-to-many. Files could be easily shared with anyone on the network. Of course, NAS introduced costs and complexity by demanding networking resources like switches, routers, and connections. It also raised such concerns as security but network zones and segmentation ensured only authorized users can retrieve resources on a server.Business processes continued to evolve and scalability became an issue for DAS and NAS. A proven solution is RAID, which replaces single disk drives with multiple ones in a single array, which can be configured for performance and data protection. Additionally, JBODs can daisy chain multiple arrays for even greater capacity and scalability.
NAS solutions eventually offered petabytes of capacity but even this was insufficient. For enterprises with immense storage needs, the breakthrough was storage area networks (SANs). SANs consolidate hundreds if not thousands of disks into a dedicated storage network that is a subsystem on the enterprise network. Servers on the enterprise network see the SAN as a single pool of storage. As a dedicated storage network, a SAN can be architected for performance and availability. Whereas NAS is good for file-level storage, SANs effectively support block-level storage, making them ideal for large enterprise databases. Moreover, SANs today can offer unified storage that includes file, block, and object storage. SANs offer low latency and resilience, but they are a costly and complex strategy.The good news is organizations of all sizes have many options to best meet their needs and budgets.
