Glossary Storage Systems, Protocols, and ScaleNetwork-attached storage (NAS)

Network-attached storage (NAS)

Network-attached storage, usually shortened to NAS, is storage presented to many clients over a network as a shared file system, accessed over NFS or SMB. It organizes data in a directory tree, enforces permissions, and records standard file attributes, such as path, size, owner, and dates.

Key takeaways

NAS is the usual home for shared business files.
NFS comes from the Unix world, and SMB from the Windows world.
CIFS is an early version of SMB.

What is NAS used for?

For files that many people or applications share over a network: home folders, team and project shares, media editing, engineering and research data, and applications that expect a file system. NAS presents storage as folders that users and servers open by path, which is why so much unstructured data in a data center lives on it.

Is NAS considered fast storage?

It can be. NAS covers a wide range: all-flash systems built for video editing, research, and AI work, and high-capacity disk systems built to hold large amounts of data at a low cost per terabyte. Speed depends on the drives, the network, and the protocol, and because data travels over the network, NAS adds a little delay compared with a disk inside the server. For the most demanding workloads, such as large simulations, organizations often use a parallel file system instead.

When should you choose NAS?

When many people or applications need to share the same files by path. NAS fits home folders, team and project shares, media and design work, and research data, and it serves Windows and Linux users from the same system. It is less suited to databases and virtual machines, which usually run on block storage, and to very large archives that are rarely read, where object storage or the cloud costs less per terabyte.

What is the difference between NFS and SMB?

NFS came from the Unix world, and SMB from the Windows world, and both present a remote file system over a network. They differ in their treatment of permissions, locking, and identity mapping. For anything that crawls a file system, the practical differences are speed and how each one reports the last access date.

What is CIFS, and is it the same as SMB?

CIFS, the Common Internet File System, is an early version of the SMB protocol from the 1990s. The name still appears in storage settings and documentation, but modern systems use SMB 2 or SMB 3, which are faster and more secure. In practice, a “CIFS share” today is usually an SMB share.

What is the difference between NAS and SAN?

NAS shares files over a network, so many users and servers can open the same folders. A storage area network, or SAN, gives servers raw blocks of storage that look like local disks, and each server formats and manages its own space. NAS suits shared file data, while SAN suits databases and virtual machines that need fast block access.

What is a general rule for tiering NAS?

Keep fast NAS for data people are working on, and move the rest down by rule:

Active data stays on primary NAS, often anything read in the last few months.
Data that has gone quiet, commonly 6 to 12 months without access, moves to lower-cost NAS, object storage, or the cloud.
Finished projects move as a whole once they are delivered, rather than file by file.
Nothing moves without a way to find it again and a plan for bringing it back.

Each organization sets its own limits, based on how often old data is reopened and how much a recall costs.