Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win


What is NAS and SAN?

Posted on 2006-06-26
Medium Priority
Last Modified: 2013-11-15
What is NAS and SAN? please give detail explain and how to choose and implement! Thanks!
Question by:mandy9
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 96

Accepted Solution

Lee W, MVP earned 176 total points
ID: 16986068
Hi mandy9,



Which to choose depends on your purpose - if you are planning on using Exchange or SQL server or setting up a cluster, then the most appropriate is usually a SAN.  If you want serverless network storage (no need for a Windows or Linux Server) to place company user home folders and/or group shares (basically File Sharing), then you want NAS  What is your purpose?


Assisted Solution

NYtechGuy earned 168 total points
ID: 16986178

NAS is more "standard" and cheaper.  It is most common in an Appliance like a Dell Powervault or a SNAP! Server.  Basically disks locally attached to a controller of some sort - could be running Windows, or some proprietary OS based on linux, etc.  Users/clients/server are able to access the information over the ethernet/LAN network using shares setup in the OS of the device.

A SAN (Storage Area Network) is much more of an investment.  Essentially, there are a large number of disks attached to "San Controllers" via fiber connections.  There is a Fiber switch involved, which allows you to connect *MANY* servers "to the fiber".  You then, in the storage controller interface (usually web based, or using an application) setup what servers are "presented" which volumes.  Those volumes then appear as a locally connected disk in the server's disk management.

The SAN is much more versatile.

What are you trying to store (what type of files, and how much size total?)
Who is going to access it (PC,Mac, how many clients)
LVL 96

Expert Comment

by:Lee W, MVP
ID: 16986243
Technically, you can get a NAS for a couple of thousand dollars or less - a little box that holds a single hard drive and plugs in to the network is TECHNICALLY a NAS.  HOWEVER, In my opinion, buying a NAS that costs less than HIGH 5 figures is pointless.  The EXPENSIVE NAS systems offer a variety of features including expandability and features like snapshots (akin to Windows 2003's Volume Shadow Copy).  Smaller units cost $$$ when you can just buy a RAID controller and a few drives for an existing server or even buy a new server to act as a file server that is cheaper/more expandable than a Snap server or Powervault storage unit.

Assisted Solution

dlmario earned 168 total points
ID: 16996266
Hi Mandy9,

the main difference (technical) between Storage Area Network (SAN) and Network Attached Storage (NAS) is the level of access.

On a SAN you access blocks on a logical (of a RAID system) or physical (of a bunch of disks) volume. There you have features like "SCSI reservation", which is important for clustering for example. SAN uses the SCSI Protocol, so every SAN disk is like a SCSI disk for your OS. You need special Fibre Switches for SAN. Speed is 4, 2 or 1 GBit.

On a NAS you access the filesystem. You have no access to SCSI commands or Blocks. You cannot format a NAS Disk, because you only access the files in the filetree. The kind of filesystem is in a blackbox for the client of a NAS system. The protocol of a NAS is mostly CIFS/SMB (Windows Share), NFS (most for Unix/Linux) or FTP. NAS handles the filelocking for you - SAN does not lock files while concurrent access. NAS uses "normal" network components.

Another differenciator are the costs: SAN storage is more expensive than NAS, because SAN is most used in enterprise high availability environments (most for Clustersystems).

An third system is I-SCSI. There you have SCSI protocol over IP. This combines the blocklevel Disk access system of SAN whith the cheap network infastructure. But be aware, that Ethernet/IP/SCSI has more overhead than Fibre protocol - but you can realize clustersystems with little money.

Hope that helps...


Assisted Solution

Disorganise earned 168 total points
ID: 17008889
NAS can be thought of as a file server replacement - you plug it in and voilla: a bunch of disk space available on the IP network.  NAS (generally) has the same kind of limitations as a traditional server, except you don;t need to 'manage' the OS - it's like a black box or utility.  In some respects its like plugging in a thumb drive to your PC to add more space, except you plug the NAS straight into the network.

SAN is something you plug servers 'into'.  SAN is method of separating hard drives from the servers: instead of having IDE or SCSI cables connecting your server to disk or array of disks, you have a fibre channel cable plugging into a switch, and from the switch to a rack full of disk.  SAN's rely on a 'fabric', which can be thought of as the SCSI equivalent of a traditional IP LAN.  By pooling the disks together and allowing them to be shared, greater utilisation may be achieved  (very simplified example: if you have a 36GB drive in a server and only use 10GB of it, the other 26GB is going to waste.  With a SAN, another server is able to use that 26GB - each 'partition' is usable by a different server.)
Since sharing drives between multiple systems inevitably introduces contention, SAN's usually employ large amounts of cache memory - the result is that most disk IO's write into cache and thus you get significant performance benefits.  With SAN's costing both arms and legs, you also get extra smarts like; snapshots, block-level replication, lots of sofware tools for monitoring performance etc

Featured Post

[Webinar] Lessons on Recovering from Petya

Skyport is working hard to help customers recover from recent attacks, like the Petya worm. This work has brought to light some important lessons. New malware attacks like this can take down your entire environment. Learn from others mistakes on how to prevent Petya like worms.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The Delta outage: 650 cancelled flights, more than 1200 delayed flights, thousands of frustrated customers, tens of millions of dollars in damages – plus untold reputational damage to one of the world’s most trusted airlines. All due to a catastroph…
Microsoft will be releasing the Windows 10 Creators Update in just a matter of weeks. Are you prepared? Follow these steps to ensure everything goes smoothly and you don't lose valuable data on your PC.
This video teaches viewers how to encrypt an external drive that requires a password to read and edit the drive. All tasks are done in Disk Utility. Plug in the external drive you wish to encrypt: Make sure all previous data on the drive has been …
This tutorial will walk an individual through the steps necessary to install and configure the Windows Server Backup Utility. Directly connect an external storage device such as a USB drive, or CD\DVD burner: If the device is a USB drive, ensure i…

610 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question