About

Storage is a catch-all term that encompasses the areas of centralized storage (questions about SAN, NAS), local storage (questions about internal hard drives, DAS), and even sometimes questions about applications that use storage and cloud storage.

Because storage has such a wide definition, it can lead to a lot of very different questions legitimately using it. Instead of limiting the scope of questions that should use storage, please be descriptive with the rest of the tags so we know, for example, whether we're looking at an enterprise block level SAN question or a VMWare datastore on a local drive question.

There are a lot of concepts and acronyms thrown around, so here's a brief cheat-sheet:

  • SAN: Storage Area Network is often incorrectly used to refer to the Storage Subsystem but actually refers to the composition of the switches (FC, Ethernet, etc), HBAs and links that connect the initiators (consumers of the service) to the targets (providers of the service). SANs and Storage Subsystems exist primarily to provide block level storage devices to servers.
  • Fabric: A single interconnected Fibre-Channel network of switches, initiators and links is called a Fabric. There are typically two isolated Fabrics in a FC SAN.
  • Storage Subsystem: A centralized system consisting of one or more Disk Controllers and Disks, often divided into LUNs and presented to initiators.
  • NAS: Network Attached Storage is a centralized storage device that provides file level storage via CIFS, NFS, or other file-level protocols.
  • DAS: Direct Attached Storage can refer to internal storage in a server as well as external storage expansion shelves attached to a single server.
  • RAID: Redundant Array of Inexpensive Disks is a mechanism of grouping hard drives to either stripe data across all of the group, mirror data on multiple drives, use one or more parity checksums for recovering from one or more failed disks or some combination of the above.

Here are a list of commonly used storage-related tags:

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