Cloud Storage Defined: NAS, SAN, and DAS

Continuing our recent coverage of cloud storage, this post seeks to clear up the different types available. Despite some new technologies starting to gain ground to take advantage of the cloud’s unique topology (see our exploration of Gartner’s 2013 Cloud Storage Trends), the most common terms relating to storage in a data center environment are SAN, NAS and DAS.

In the world of the data center, it is generally wise to keep separate the networks used for access to servers vs. storage. This prevents access problems and helps with redundancy; when one part of the network has issues the other parts remain unaffected. The major differences between different storage systems for data centers is whether the storage disk is attached directly or through a network.

Storage Area Network (SAN) – Both DAS and NAS can be considered part of a Storage Area Network. These other terms describe the type of connection, while a SAN is any combination of storage drives and connections used to access them. However, SAN and NAS have key differences in their file structures. SANs basically consolidate many different dedicated storage units through high-speed networking. The file system on each section of a SAN is dedicated to a single server and dependent on that server’s system, simply relying on SCSI (small computer system interface) to transfer information.

Direct Attached Storage (DAS) – DAS connects directly to servers via a Host Bus Adapter, allowing direct access. Because this is fairly simple and dedicated, it can provide better performance and has less opportunity for interference or downtime. DAS is a good solution for databases and clustering, among other implementations.

Network Attached Storage (NAS) – NAS devices are storage arrays that servers connect to via IP network, usually via CIFS (common internet file system, usually used for Windows environments) and NFS (network file system). NAS can be set up as a dedicated solution, ideal for intensive workloads like archiving, e-commerce transactions, Big Data, and rich media.

Posted By: Joe Kozlowicz