SAN vs NAS: Storage Technologies Compared

SAN vs NAS: Network Storage Compared

This is a question that many network admins struggle with: SAN vs NAS – which is better for their network’s storage needs? The answer lies somewhere between the type (and quantity) of data the machines on your network will be sharing; the number of computers and other access devices that will be using the network; and how important data security is to the company/organization and to those who’ll be accessing it. There are many other considerations to be made – the most important of which are explained as you read this page.

Storage Area Network (SAN)

Storage Area Networks are used by large corporations, charities, organizations, schools, and more. A typical SAN is made of several storage devices; with tens or hundreds of different storage devices, often containing thousands of storage arrays within it. They require the use of SCSI Fibre Optic Channel setup which is physically limited to a range 6 miles (10 kilometers), and always contains an FC-AL data switch, or SCSI hub to manage data transfer allocation.

Information handling with SAN:

  1. Information travels much faster due to the fibre optic connections, and because the information transfer occurs in blocks of huge data, with a specific number or meta-data assigned to each individual block (as you’ll learn when you read further, NAS transfers individual files, rather than data blocks).
  2. Each storage device in the network updates as changes are made anywhere within the network – i.e., each device is a mirror of the other. This means that there’s less chance for data loss if a server crashes.

You need to set up server class devices wherever LAN (Local Area Network) connections are going to be, which can be a limitation or a benefit, depending on your specific network needs:

The need for multiple server-class connections with SAN can be a definite limitation, if you’re building a publicly-accessible network and want people to be able to connect easily via a LAN with their own devices (and operating systems) over large distances, such as those found in a large-scale shopping mall, theme park, or industrial complex. These intermediary devices can fail, and also require regular maintenance.

The need for a server-class device with SAN is a benefit, if your network contains millions of megabits of data that’s constantly updated and the clients in the network need those updates in real-time (remember that range is limited to only 6 miles). Think of the benefits to a large hospital, for instance: large amounts of patient and administration data needs to move from one department to another quickly and seamlessly to maximize the flow of information and speed of service.

Network Attached Storage (NAS)

NAS is a cheaper, flexible way to set up a network, but it has both pros and cons when making the comparison between NAS vs SAN. Network Attached Storage set ups use a single data storage point, with a few or several storage disks (typically configured in RAID 0 or RAID 5), that connect users through a single main head unit that transfers information from the server out to its clients via an ethernet cable (sent directly to the client through a hub – wirelessly or direct from the cable).

The beauty of NAS is that there are no real distance limitations. You can transfer data anywhere the Internet will reach, including outer space for that matter.

Information handling via NAS:

  1. Anyone can connect to the network and see the publicly-accessible files that are stored on the network. Take a moment to think about how your favorite online file-sharing network needs to make data readily available to people regardless of whether they’re in the United States, Russia, China, etc. This type of set up is also used in school settings where students complete tests and assignments online.
  2. Storage devices are limited to the server and back up servers. If you aren’t diligent about doing back ups, there’s a potential that a crash could leave you without your data.


  • SAN transfers at a rate of 1000mbps of information; NAS can handle approximately 600 to a maximum of 800Mbps currently.
  • SAN handles entire blocks of data at a time – vs NAS only working with data at the file-level.
  • SAN is heavy on bandwidth due to the fact it moves blocks of data at a time.


  • NAS uses ethernet, of which the next generation is already in beta, with projections being made that speed increases will be in the range of ten times what they are currently (600×10= 6000mbps) – SAN is fast and the next SCSI version promises to double the current speeds (1000×2=2000Mbps);
  • NAS can be world-wide – SAN is limited to a 6 mile-radius and doesn’t yet have a large enough reach to be feasible for all of a company or organization’s data needs.
  • NAS is reasonably easy on bandwidth because it transfers at the file-level.


The NAS vs SAN battle has been going on for a while now. The good news is that the battle is almost over. Several developments such as SCSI over IP, and Open Storage Networking (OSN) are paving the way for faster data storage and data transfer, and both NAS and SAN networks will quickly become a thing of the past. Take care to mull over your own network storage and data transfer needs, and compare them to the advantages and disadvantages you’ve learned about here today.